Oh yeah, missed that requirement for your character. Level 2, huh? Tricky one...

Be a Genasi, choose Specialized school and.... one more thing, and you'll have CL 5 in some kind of spells.

I seem to recall an old 3.5/.0 feat, item or ACF that allowed you to take a Focus that would replace all other focuses for spells provided it cost more than the price in the spell description.

Anyone know anything like this? I can't remember any more details than that, just wondering if it was somewhere I hadn't looked.

I played AD&D back in the day (1st and 2nd edition). I'm also pretty familiar with 4th edition. I've never played 3.5 but that's by far the most popular version on this site, so my question is how many and which books do I need to be familiar with to start playing 3.5?

Only the players handbook, really.

If you're familiar with the basics of D&D (and have a GM / other players williing to help), you could even skip the Player's Handbook since most of it is Open Game Content and in the SRD

FATE

If I want to run a game using the FATE system, would I be better off running FATE 2.0, or SOTC?

It really depends on what you want this game to DO.
SotC is great, imo, for pulpy action, like steampunk or the like.
FATE2.0 is quite a bit more generic, but it can be adapted (with effort) to a much wider variety of games.
If you're willing to branch out to other FATE-based systems, though, the likelyhood that FATE2.0 will be the most suitable drops significantly.

I'm looking for something that has a very flexible and description-based magic system.

Neither FATE2.0 nor SotC have a magic system that is particularly well fleshed-out, imo, as 2.0 is a generic system intended to be built upon and SotC just isn't a particularly magical genre. The magic systems of both seem, to me, to be tacked-on and skeletal.