Hello TysonP,
Welcome to the hobby.
You have "spenders". They are a good entry point to the hobby as you get them for face value! I highly recommend that you buy the Charlton Catalogue, and attend a couple of coin shows to gauge your interest.
Most people are content to collect a few bills from circulation "for the future", but some of us take it to the next level by assembling type sets, signature sets, etc...
Collect what you like. If it appeals to you for whatever reason, keep it.
Don't try to make an investment out of your collection...you may end up disappointed.
In response to your second question, I collect $1000 bills. Not because of their rarity or value. I just like them!
It's a nice way to save too...
Dean