A:AnswerYes it will fit just fine in that white slot (which is PCI Express). Even if you have an older version of PCI-E, the slot is backwards compatible. This means you can buy a PCI-E 3.0 card and it'll work in a PCI-E 2.0 or 1.0 slot.
A:AnswerYes it does... one bracket supports VGA / DVI and the other supports HDMI / DVI. Both brackets are half height.
I used the HDMI bracket for my HTPC install and it worked perfectly!
A:AnswerYes, I purchased this specifically to upgrade my Dell XPS 8500 to Windows 10, and it works great. Windows 10 identified the card and automatically installed the proper driver.