Consult the manual for preferred NIC type.
Motherboard
A pico BTX is 10.5"x8" and only supports one or two expansions slots, designed for half-height or riser-card applications. A microBTX is 10.4"x10.5" (264x267mm) and it supports up to four expansion slots.
It depends on the motherboard. If your motherboard supports core i3, it is possible, if not it isn't.
Yes you can. There's also an option in the CMOS setup to enable or disable this feature if your motherboard supports it.
Yes. The Intel D945GNT motherboard supports dual-core Pentium D processors.
assuming the older mother board has similar sockets and slots for your current devices parts (and your motherboard supports those devices) you should have no problem downgrading
Yes as long as your motherboard supports it.
No. A motherboard will specify what type of memory it supports. The DIMM slot for DDR,DDR2 and DDR3 have different footprints.
It should be compatible because the motherboard supports DDR3 ram and the Corsair CMZ8GX3M2A1600C9 Vengeance is DDR3!
by knowing 1. the socket on your motherboard and 2. the frequency it supports
It is difficult unless the motherboard supports DDR slots.
A Pentium 4 processor, and a motherboard that supports it.