if by moderate OC you mean 4.3ghz or south of it, then the 3570K wouldn't be so bad a choice while offering a performance close to or better than a 2500K@4.5Ghz and keeping temps under check. buying it for PCIE 3.0 and/or thunderbolt ports alone isn't exactly a good reason at least for now anyway. by the time they do become highly relevant in a few years time, as stated above, you're better off buying a new CPU+mobo.
like the rest, i definitely can't recommend you getting an H60 unless you're buying a pre-built and this is the only choice they're offering you. Hyper 212 EVO, or a Noctua NH-D14 at worst (cost-wise), all the way.
the only time i would recommend an h60 s if you plan to buy a Dwood gpu bracket at some future date and water cool your gpu. if not, the h60 is not worth your time. If you wanted a cheap watercooling unit, I believe the Antec Kuhler 620 goes for less.
Hmm. I guess I will consider the Hyper 212 evo. Should I get the 3570k or 2500k with it? I heard Ivy Bridge is having some thermal issues. I heard the Hyper 212 evo doesn't come with pre-applied paste, so I guess I will buy some Shin-etsu x23.
strictly depends on how much of an OC you're looking at. i'll mention again; the 3570K tends to overheat when you raise the voltage, usually around 4.2-4.3ghz. this should give you a performance close to or even better than a 2500K OCed at 4.5ghz. consider as well that you said you planned to OC this moderately, and these OC's i'm mentioning are somewhat beyond moderate already. at the same clock speeds, say 4.0ghz, the 3570K will win in most, if not all, cases.
if you actually have plans to OC beyond 4.5ghz and get a custom water loop, then a 2500K isn't so bad if you're really concern with heat. below that, and on air cooling, i highly recommend the 3570K if money isn't a big concern.