Yeah it is Micro, I misremembered M-ATX and M-ITX, they're still compatible
It's not a bad GPU, but I know the XFX has a great cooler, particularly in terms of sound levels.
GPU's nowadays are all PCI-E 16x, though they can run in PCI-E 8x/4x in SLI/Crossfire configurations, it's a very well established standard. So as long as the card is modern, it will definitely fit in the board.
Yeah it is geared for an average user, "gaming" boards won't affect performance, they just come with an overclocking chipset and a revamped power delivery for overclocking. It might also come with some extra PCI-E lanes, though that's not necessary to be honest.