ph33r = fear
b4k4 = baka = idiot
fsck - Unix command, often used as slang in the place of that other 'f' word due to their similarity.
Piro's rant talks about l33t speak and how Piro's Quake character is based on some FredArt drawings of "RuriQuake" that can be seen here, here, here, and here.

Piro speaks:
And it's not REALLY 'Ruri' here... perhaps the best way to look at the quake model is 'a quake model cosplaying as Ruri who happens to have hair very similar to Piro (note the bangs have become ponytails ^_^)'
In MegaQuake mode, Largo's model is LargoQuake.md3 (note the big hair) and Piro's model is PiroQuake.md3