Assuming you are running Windows, you'll need to plug a monitor into the second card or use a dummy plug
http://blog.zorinaq.com/?e=11
http://www.xtremesystems.org/forums/showthread.php?t=200444

Also, general consensus for overclocking on Windows is to use MSI Afterburner

DON'T!!!!!!!!!!!!! THAT'S A SCAM FROM YESTERDAY

I am too beginning to think it's a ponzi scheme
http://www.youtube.com/watch?v=GDcdE9ngx08

Maxxx, if you need Ubuntu USB with persistence, follow this tutorial
http://www.infosecramblings.com/backtrack/backtrack-4-usbpersistent-changesnessus/

I am from anonymouse. I can confirm that this is serious business and we'll be joining you with our loics

The internet. It's the place where one idiot writes about another idiot doing stupid things. Once it gets published, a lot of people with no life care about it.  Fascinating!

I think they just should stay in the kitchen where they belong
http://www.youtube.com/watch?v=LS37SNYjg8w

Do you also apologize to schizophrenics for not knowing the name of their imaginary friend?

Try pheonix or diablo miner

I think that's it. You won't be getting more than 8 connections if you can't bind your clients to 8333 port. If you have your external IP in .conf file this will allow your clients on Macbook and Win7 to instantly download the blockchain from your Mac desktop even if that's the only connection.
I would remove noirc=1 from .conf. If you leave it there it disables IRC peer discovery method. When you take your macbook with you to another network where you have access to port 8333, you'll benefit from being able to use this method.

1. This setting is for people who use proxies. The example "proxy=127.0.0.1:9050" is the way bitcoin can be used on Tor. Localhost acts like router/proxy.
2. Already mentioned - IRC peer discovery method
3. Is for controlling Bitcoin via Jason-RPC

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.

Brilliant!!! 

You should sleep less 
On a more serious note, I think [Tycho] is working on email notification

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

No. 10.0.0.100 is the IP address of your Win7 virtual machine. You can find out your external IP by visiting http://www.whatismyip.com/

You don't have to do that. If temps get high just write a script that lowers core clock. Thermal protection is there by default

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

Glad I could help.

If you wonder to some different network, like 192.168.*.*, you may experience connectivity problems in your virtual machine. All you have to do then is change "Internet protocol version 4" settings back to "Obtain an IP address automatically" and "Obtain DNS server address automatically"

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 program that does that, but on a macbook pro - I am confident, you are safe.

This is just for your home network.