Air cooling is plenty to cool an OC'd i5-2500k. Hyper 212+ is a good choice, or the slightly updated 212 EVO. This will easily cool 4.5GHz OC.
Yes 750w is enough for 560Ti in SLI with CPU and GPU over-clocking.
PSU recommended brands include: Corsair, XFX, SeaSonic, Antec.
Case recommendations: Well the case should be your own choice really, its possibly the most important part of the build for some people
Any mid-Tower ATX case would be fine. Cooler Master's HAF series is a popular choice. But ultimately, go with something you like the look of yourself