All pci X16 2.0 cards are backward compatible.
Any PCI Express card will work.
yes, if your motherboard supports crossfire and your graphics cards support eyefinity (at least 3 of your monitors will need to support display port, or you will need to purchase active adapters for them)
the Intel is integrated into the motherboard and the radeon is separate is the visual difference....the latest integrated gpu's are still weaker than cards from 2001 from companys like ati or nvidia......
The best graphics card to run in a PC will be based on what your motherboard is able to support and what type of connection it has. Normally, boards with PCI express are good cards. However, some of the best cards are Radeon cards or Invida cards, which are not cheap normally.
Peripherals relative to a motherboard are: power supply unit, CPU, RAM, HDD/SSD, optical drive, graphic/sound/LAN cards (if not integrated).
No it cannot you will need to get a agp card or upgrade your motherbord.
Only if the motherboard has a PCI slot.
HD4850 1gb
Yes, Graphic cards PCIe x16 V2.0 compatible ARE fully compatible with PCIe x16.
it has more bandwith in other can get more performant expansions for say raid cards or more commonly graphic cards
Riser
I'm sure it will, it will just run at 4X.