Bad Ass: 30-40 hours for both ME1 and 2 is pretty normal, I think, though you can stretch it out a lot longer than that. Didn't think either of them were particularly difficult on lower difficulties, though you might have to adjust a bit when you first start playing, but since ME is kinda a hybrid of RPGs and FPSs its not a super difficult version of either. Stats in ME1 are pretty simple(you have like 10 skills per character to upgrade and that's it, and it's fairly obvious what you're using and what you aren't), in ME2 it's even easier since you don't end up making many choices for anyone but your PC. Gameplay is a lot better in ME2 than ME1 but it's way too storydriven not to start with ME1. ME2 also has the ability to be reasonably difficult if you start an Insanity file at level 1, it's not like ultra difficult but it punishes you for doing stupid shit... it's a fun second playthrough sort of thing once you get that far.
I picked ME up last summer because one of my friends was nagging me and couldn't put it down, by the end of the next week I had ME1 and 2 beaten. Have beaten them both something like 4 times in less than a calendar year, it is really good stuff.
Cooper - My original ME/2 file is probably what I'll use, I had thought it was suspicious the first time I played through ME1 that I had all these decisions that seemed to effect the future of other races, so I made sure on the file I ported to ME2 I kept as many seemingly relevant people alive as possible in case it mattered in ME3, and then did the same in ME2 when you had decisions to do so on loyalty missions and such, in addition to keeping the suicide on the suicide mission to a minimum. The only thing I thought I was going to regret was going Paragon on the last mission, but judging by what I've seen of Cerberus in ME3 trailers that was the right call, too. The second time I played through ME2 I basically made the same decisions I did instinctively the first time, just repeating everything after re-transferring from ME1 so I had an Insanity->Insanity clear to move over in case there's an achievement for beating the game on the highest difficulty all three times or something.
I'll play through ME/2 again during winter break next year just so its fresh before ME3 comes out, but I'll probably stick to my guns on the save file.