I understand your dilemma, hehe!
For the info, it's simple. If you want i5, the mobo needs socket 1155. If you want the FX, you need mobo with AM3+ socket. This info should be displayed on the page you buy the mobo from, or at least it should say compatible with ivy bridge (the i5-3570) or sandy bridge (i5 2500) or FX. If you buy from newegg, you can search for mobos by selecting the right socket filter on the left side of the page. The i5 is a bit more expensive but more future proof, and it's a beast when overclocked. 😀 And it will also give better results with your video card, even if you would OC the FX-6300.
EDIT: Yes, an entry level mobo will be fine with a reasonable OC.