One other quick noob question. The address is only for people to transfer coins, once the transfer has actually occurred and been confirmed, the "keys" are in the wallet. So technically, you just copy the wallet.dat and then could load it on a new bitcoin client installed on any machine, which creates a new address and once you load the blockchain, your coins would show up again.
Well the client may create a new address but your coins are sent to the "old" addrress. Still the first part is right on the money/coins.
The block chain is a record of where all the coins are at. For example 123 coins at address A, 999 coins at address B, etc.
The wallet coins the public keys (which aren't secret) and private keys (which are). The public key allows the wallet to lookup in the block chain to see if any of those addresses have coins (value >0). The private keys ensure only the holder of the private key can "spend" or technically move coins attached to those addresses.
So yes if you have 100 BTC sent to Address A and you take a copy of wallet.dat, install it on a new machine, let that machine download the blockchain your coins will "show up" there.
I like the idea of storing the coins at the pool, any real security reason not to do this besides the pool operator running off with them? Or is that even possible?
It certainly is possible. Remember in Bitcoin he who controls the private key OWNS the coins. If the pool walked away with your coins they are gone. No way to ever get them back. Technically although the pool may show your balance is 123 coins as long as they are in wallet the pool controls for all intents and purposes they are the pools. Personally I wouldn't leave coins at the pool.
BTW, I have read the security guide stickied above, the wiki's etc. not just trying to take the easy way, but the security aspect does have me a bit confused. Basically, I only plan on offloading coins every few months to help pay down some of my hardware costs, but I anticipate saving most of the coins I mine and don't want them to get ripped off.
Let's say you get 100 coins in a particular wallet file, could you just copy that file to a usb drive, remove it, delete the one on the computer and let the bitcoin client create a new wallet.dat?
Yes although technically you don't even need the client to create a new wallet.
Basically have a few usb drives(backed up of course) with multiple wallet.dats with different amounts of coins?
Then just load a particular wallet when you want to trade?
Yes that will work. It is sometimes called "cold storage".
Your wallet doesn't need to be online in order to receive coins because the value of addresses are stored in the blockchain.
You could check on the value of your address by using the block explorer (just enter your address and you can see the current value at any time).
I would make more than one backup (w/ encrypted wallet file). If the copy of your wallet is lost, corrupt, or you forget the passphrase then those coins are gone forever. Remember the person who has the private key can move the coins and if nobody has the private key well then those coins will never move ever again.