fteqccgui has a simple grep feature that can scan through all of your mod's qc files to find both where thing are defined or used. notepad++ likely has a similar feature but I don't know if it'll scan other files or not, I can't say I've ever used it.
For instance, grep for 'impulse' and you'll find the various places where the impulse handling stuff is (eg: the bit in weapons.qc where it handles impulse 255 and invokes QuadCheat). From there you can find super_damage_finished, and then find your way to powerup_touch so you can find the names of the equivelent fields for the other powerups. Easy.
The term 'command' usually refers to console commands, using that word to refer to a function is something that only someone who wrote too many shell scripts would do...
that said, quake's console commands are very rarely camelback like that, so anyone who's been around quake a while should realise that pretty quickly (recognising the individual functions makes it a bit too easy).