So far behind
Seriously considering picking up ME1 and ME2
Do it, at the very least read up on ME1 and start with ME2... it was a whole lot better than the first game.
I was told you had to import a party from ME1 into ME2. I didn't completely buy the statement since while old style RPG series did that, they don't really do that currently.
You don't have to. You can go through and start a new character for 2 and be fine, but you'll miss a lot of back story and a lot of your choices in 2 will feel like they're a lot less important because you don't have the background.
I'd advise playing through both though. Both are good games. I think 1 has a bit more RPG stylings and a broader scope. Stronger characters and storyline. ME2 is a pretty short game unless you do all of the side missions, and it plays like the middle book of a trilogy--more of a story bridge than its own powerful entity. Its RPG roots are stripped back a bit while the gameplay runs faster and the shooter elements are much more refined than in one.
I think it's worth playing both, they're both great games. Different...when I switch between the two, it takes me a few missions to get used to the differences. 3 supposedly brings back a bit more RPG elements and continues to refine the shooter elements.