Advancing famaliars

[Silveras]

I had a similar question to this thread, so I figured I'd piggy-back.

It's clear that familiars don't gain feats or more skill points b/c they don't gain new levels or hit dice.

However, they DO gain more intelligence. SOooo... do they gain more skill points as a result of their intelligence modifier? Do they gain more known languages as a result of their intelligence modifier?

And is there any reason why a familiar cannot take class levels just like any other creature in the Monster Manual?

Well, first off, not all creatures in the MM can take class levels. If the advancment line says "By character class", they can take class levels. If it says "By Hit Dice", you use the "Advancing a Monster" rules instead. If it says "--", it means they do not advance at all.

Familiars are generally taken from the "By Hit Dice" or "--" groups.