Good morning
1. Yes, you can use walllet.dat on Linux, OS X and Windows
2. Depends on OS and "what kind of sleep" but generally yes.
3. That is a good question. What OS are you on at the moment? If it's mac, did you put it in
I copied the whole sample code from https://en.bitcoin.it/wiki/Running_Bitcoin . Alter settings to your needs. It worked well for me.

Bitcoin client has several ways to discover nodes. One is - it connects to IRC and queries other nodes in the same channel for their IP addresses. Once it knows the IP addresses, it tries to connect to them on 8333 port. If the port is closed, it cannot connect to that node. It is not a big problem because there are other ways that Bitcoin client can connect to the network. For example, it has inbuild list of reliable nodes and these 8 connections are usually the ones. You can also specify nodes manually with -addnode= switch like we did earlier.
The real problems begin in certain circumstances. For example when port 8333 is closed + reliable nodes are down/have to many connections/exceeded their bandwith. So you can see that in some cases even if you are connected to the network you have to wait a long time before you can update your blockchain.
For more info on how to run multiple clients on a home network using different ports read this: http://forum.bitcoin.org/?topic=589.0
I personally chose another strategy. I opened 8333 and forwarded to one of my computers, which is on most of the time. Now whenever I want to use a client on another computer, I just start it with -addnode=my external IP. What this does, is connects it to that computer which is on most of the time. Since it has up to date blockchain and my client on the other computer doesn't have to wonder halfway around the globe looking for nodes, download starts immediately.

Sorry, it's 4:02am where I am. I will be back to answer the rest of your questions ~12:00pm GMT

We connected your virtual machine to your home network as a separate computer. Now the client on Win7 is binded to 8333 port on your router. You can not bind another client to the same port. Although, if you start a client on your OS X and if it connects to the network there is no reason why you can't send coins between them.
In fact you could start your OS X client and specify -addnode=your external IP. This would connect your mac client to your Win7 client.

edit: In order to run multiple clients on one external IP you need to use different ports for each client. I don't have in depth understanding of that so I'll leave you to research it on your own

We connected your virtual machine to your home network as a separate computer. Now the client on Win7 is binded to 8333 port on your router. You can not bind another client to the same port. Although, if you start a client on your OS X and if it connects to the network there is no reason why you shouldn't be able to send coins between them.
In fact you could start your OS X client and specify -addnode=your external IP. This would connect your mac client to your Win7 client.

edit: In order to run multiple clients on one external IP you need to use different ports for each client. I don't have in depth understanding of that so I'll leave you to research it on your own

You sir are a gentleman and a generous one at that.  I thank you so much.

Congrats! You are now running full node. Give it some time and it will find other peers.

You should dissable UPnP button.

Opening a port is putting trust in the application that is listening on that port. I am not a developer and my opinion is just that, but I think Bitcoin is very well written and it exposes you to no more danger than keeping firefox open.

Other programs won't be affected unless you have a program that listens on port 8333. There's some MS Windows Server programs that does that, but on a macbook pro - I am confident, you are safe.

This is just for your home network.

You are nearly there.

Choose port forwarding. Custom service. Start and end port should be 8333 and IP should be 10.0.0.100. I'm not sure about the protocol, so choose both - TCP and UDP.

IP address: 10.0.0.100
Subnet mask: 255.255.255.0
Default gateway: 10.0.0.1

DNS servers:
208.67.222.222
208.67.220.220

We are now configuring your home network which is separate from ISP

No, by default VMware puts you in a NAT network. You have to change it to Bridged network so that your virtual machine can connect straight to your home network. It's the lower right conner of VMware machine and looks like <...>

To get a static IP in Windows go Start>Control Panel>Network and Internet>Network and Sharing center>Change Adapter Settings
Right click on Local Area Connection>Status>Properties>Internet Protocol Version 4>Properties
Change to "Use the following IP" and enter the appropriate IP, Subnet mask, Default gateway and DNS server.
Check "Validate on exit" and press OK. That's it.

Open Windows in VMware Fusion and then choose "Bridged" network(lower right corner). Also, set a static IP address in Windows. Then open/forward 8333 port from your router to that IP address.

You cannon make more than one client listen on 8333 port if you are behind a router

thx, seems to have fixed it for me went from 5-10 connections to 80+

Yawn.

These stories come out every couple of months, and have for years, and years, and years.

The dollar has some big problems, as does the US in general, but there is simply no viable alternative, and no prospects for an alternative.  Also, nearly every man, woman and child on the face of the planet has a vested interest in preventing a full blown collapse.

America has scared all entrepreneurs overseas, to its own detriment.

  A great opportunity presents itself and instead of a burst of competition and job opportunities, we are cowardly in our fear of the FED and the legal system. Sure we will try to play it safe and report and provide information off of others works and efforts but why doesn't the american entrepreneur go down to the Bank open up a business account and start an exchange? Because we cower in our fear of the FED and lawsuits. The little guy is being held down by fear. It is a sad thing, we see news articles of aldermen calling the Police on the kids selling lemonade from their stand. And the police respond and shut down the operation. Imagine what would happen if the 'Kids' were actually making money and had to hire other people. They would probably get felony charges.

  Common sense has left and been replaced by the police, lawyers, and the courts. Small startups have to already be successful to properly wind through the legal system and avoid all the traps set by the corrupt to avoid competition in their industries. Does the government supporting companies like GE from others help the country by protecting GE? I propose, NO. Sure GE has thousands of employees paying taxes and supporting the economy. However, if 10,000 small companies sprout up with 10 employees each. Who is supporting the Government more, GE or the small guy. Oh, but wait, the small guy can't get Lobby's to bribe lobby the government. So take heart, little guy american BitCoin entrepreneur, if you try to become to big in the financial industry, you will probably be arrested, sued, and sent to jail. Then Wall Street will take over for you and "do it right".

  I am for the Honesty in an American Exchange with the protections provided from corruption but I don't want it to come from Wall Street. All that the reasonable person would want for protection, is dispute resolution, accounting disclosure, ease of transactions. We 'adults' should know that we are taking a risk. And if we loose our money from declines or bad trades, Don't go crying to DADDY. It is my personal belief that the move for Government Regulation and 'Control' is from 'Kids' never learning to be adults. They wan't the Government 'Mommy and Daddy' to help them out and save them from their mistakes.

So in conclusion, American Entrepreneurs, don't work in Fear, fear of the government, fear of the law suits, or fear period. If as I suspect, if you take the risk and grow rapidly and "hire" employees, you just might start a new revolution in financial industries. Just one suggestion please, Don't put your headquarters in New York or California.

LOL!  What nonsense!  There has been numerous articles from real economists pointing out Krugman's poor prediction record!  One I've seen actually demonstrated how Krugman is only slightly better than throwing darts at a dartboard blindfolded.  If you want to see an economist with a real track record for accuracy, try Mish (http://globaleconomicanalysis.blogspot.com/)  Peter Schiff (http://www.europac.net/) or Rich Maybury (http://chaostan.com/).  All of these guys actually make money, real fortunes, based upon their predictions.  Krugman makes money selling advice to readers of the NYT.  He's the economic version of "ask Nancy".

If you are taking your advice from someone who doesn't make a living from his own advice, you are an idiot.

Open the 8333 port

Well, your day-to-day account should be backed up regularly, but hopefully you aren't keeping a huge balance in there anyway, so if it is lost, it would only be a few thousand dollars worth of bitcoins at most.  You could keep a copy of your vault backup in a safe deposit box too, so if you suddenly have need for the equivalent of tens of thousands of dollars worth of bitcoins, then you could grab the backup from your safe deposit box and start it up.  I would imagine you could constrain yourself to less than 100 transactions from this account per lifetime to ensure the resiliency of your other backup.

I agree the current solution is not ideal.  Ideally, backups WOULD be 100% persistent.  I am just saying that there are easy ways to work around the issue if you know what you are doing.  For the general populace, we do need a better solution, as you KNOW there will be people out there who don't understand the process.

I would advocate that people choose whether to generate a new address for the "change" in a transaction, or whether to just keep them at the old address.

I still think a backup service, whose sole purpose is to back up wallet files and release them only when required by the individual or a lawyer on behalf of an individual's next of kin, would be great.