The only ones that you need to be pretty close with are the 5/16×1.25″, and really only 4 of those are critical so you could get out mr angry if you need to. The rest, longer is probably better than shorter.
As for the heads, as flat as possible (only a few where this matters so you could grind if needed) and no countersink heads.
I did what I could to make everything pretty universal, Most anything within reason should work. If you are using metric screws, some of the nut traps will not trap the nut, which is fine. Some will just need some glue (I use it on mine anyway) or some will need needle nose pliers. No big deal.