No, you cannot.
No.
You cannot actually insert pci slots into a PC since pci slots come inbuilt on the motherboard. so the no. of pci slots u have depends on the motherboard.
PCI-E 2.0 is reverse compatible that means a motherboard having PCI-E can support a PCI-E Video Card.
A motherboard
Only if the motherboard has a PCI slot.
Four is a good number for most people.That gives you a lot of flexibility.
PCI express is faster
Yes.
The only way to do that is to change the motherboard.
Pci cards
Pci cards
Not sayin :P haha