Partial list
I've assembled a partial (repeat, partial) dictionary of terms on the GateGuide. Look in the Codex, for the "languages" entry. I'm adding more words as they appear - and as I have time ;-> I'm a few episodes behind Showtime's schedule, though, so any of the new stuff from fourth season won't be in there.
As far as I know there isn't a collected grammar somewhere, and I haven't been paying enough attention to know even the word ordering/basic syntax. I do know that the Klingon language is partially based on Chukchee, an Inuit language. The morphology and syntax are what's similar - not the lexicon (actual words)...so Marc Okrand had something of a head start.
In the movie Stargate, it was implied that the language of the Goa'ulds was similar to ancient Egyptian - which would make sense, since the movie posits that the Goa'ulds were behind most of the myths and legends of Earth, as well as the founders of some of the cultures. Again, in the movie, Daniel could communicate with Ra after spending some time figuring out how the language was actually spoken, and how it had drifted (which apparently wasn't much). In the series, Daniel seems to be the person - besides Teal'c - who can best translate spoken Goa'uld, so I think that the producers are sticking with the premise that Goa'uld is supposed to be similar to ancient Egyptian. In the episode "Serpent's Song", the actor who played Apophis essentially spoke gibberish, while Michael Shanks was given lines written/translated by a linguist or a specialist in ancient languages. I don't know if they do this for the other Goa'uld lines in the show, though.