You need to remove the two pins that hold the front sight/gas block (they're tapered on most guns so only remove one direction), and the gas tube roll pin after removing the flash hider.
Action Block to hold your receiver in your vise
A wrench for the FH
A poly or wood block with holes in it to back your FH while you pound out the pins
A set of short, high quality steel punches for the FH pins (brass, or long punches will bend, but will work fine for the gas tube roll-pin)
A big hammer
IMO the barrel is the hardest part to install correctly for a newb, and an A2 gas block is the hardest part to remove.
ETA: You should check out ar15.com, they have a step by step assembly guide.