You should be able to post to bios without cpu and and download new bios to usb sick and flash it. I've done it before and it worked. That was on older asus board.
What are you going to do with your pc? Gaming or video editing/rendering or multi use?
Fx is good cpu for video stuff and gaming but for single core use i5 is better. I've owned fx 8370 overclocked to 4.8 and not I have i7 4790k and I see difference on single core that i7 is faster. Gaming is the same and video converting/ripping is the same performance. Plus my i7 runs a lot hotter than fx about 10 degrees on the same cooler which is h105 so I don't know how that works cause i7 uses less power. Forums are flooded on that topic. I5 is kind of hot too and don't expect stock cooler to cool i5...you will have to upgrade at some point.