Hi, Yes, micro atx should be fine.
Mine has 5 pci.
Just check the dimensions of your video card
Gaming usually means that a mb is fully over clockable and usually very performing.
With your nice cpu I don't think you need to overclock.
Just ensure you configure properly your Ram, disks/pci disks.
pS: this is my idea but an external sub hub is not very different from a pci hub. I prefere to have a 200€ industrial , wide temp range, external hub than rely on pc usb.this is a mith created by device makers to justify timing issues. Pc native sub ports are wired to an on board hub worths 20$.