These won't be changing because all of our weapons are the exact same as the original game in every way.
Damage, Rate of Fire, Penetration, and other values all remain the exact same, with some tweaking on some of the weapons such as the Autoshotty and RCP-90 to keep them balanced.
A headshot does 50 damage (1/2 life at full health, 1/4 life with armor), and then there's the knockback + invulnerability period on the target that you've hit. This is a gameplay feature from GE64 brought to GES, making insta-kills impossible.
Hit registration is at its absolute finest right now. Players move more slightly more slowly than other games (7/8 the default speed), and many optimizations to Valve's existing code have been made to further enhance hit registration.