Mark All Courses Completed
Browse to your game directory and open the file yourname.txt in the \System\Save folder. Replace your line with this:
511,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15 ,15,15,15,15,15,15,15,15,15,15,15,15,15,0,

Note: Always make a backup before overwriting files.

All Weapons
Hit the tilde (~) key, and type out "mpcheat changeclass #" (sans the quotes) where # is any of the following:

R - M16A2
AR - SAW
G - M16A2 (w/ Grenade Launcher)
S - M81 (Sniper)
AK - AK47
S24 - M24 (Sniper)
F - Fists
M4A1 - M4A1
AK74SU - AK74SU
GP - AK47 (w/ Grenade Launcher)
RPK - OpFor Machine Gun
SVD - Dragonov Sniper Rifle