For screws, the button head screws that use either a hex (allen) key, or some have used button head torx screws. Grade 8 screws are most commonly used. Also some have wanted the screws to resemble rivets so putting the screw into a lathe (if you have one), or into a drill press then turning on the drill press and using a file - put it to the sides of the screw head and that way it can be reduced to more closely resemble rivets.
10-32 screws for the rear trunnion, I use 1/2" length. (4 total)
10-32 screws for the front trunnion, they are either 3/16" or 1/4" in length.(6 total)
8-32 screws for the triggerguard, I use a 1/2" screw and trim it to size. (5 total) I'm sure a 3/8" screw would work too. For the triggerguard also, you could use 8-32 nuts on the inside of the receiver or you could use a nut on the rear most screw and make a plate for the 4 screws in the front of the triggerguard. The plate would basically be made by drilling and tapping it for the 4 screws, this way nuts won't need to be used. Hope this helps.