Re: Graphics card
You have a PCI-E x16 port which is great, but I see it's a MicroATX; does this mean your computer case is also MicroATX? In other words, is your case titchy? If so, then you'll probably (almost certainly) be limited to a half-height graphics card. Power is of course something to take into account, and more so if your computer is a titchy one, because some of those types (Flex, I believe they're called) tend to have unusual PSUs which are difficult to get ahold of, let alone with a decent wattage. 'n no, you're safe; RAM and VRAM are totally different, in terms of compatibility (I've certainly never heard of, seen, or experienced any such issues) and so you could get a GPU with GDDR5, if you wanted.
If you're after further help, it would be good to post your PSU, case, budget, what you'll be using the GPU for, and how fussed you are about FPS.