Two sections of this site will be interesting for you grammar-wise.
Beagan Gràmair - A Bit of Grammar - Explains how the pronunciation works, and covers some important grammar points. Some of it is written in a humorous way, so it's actually quite fun to read. It uses the IPA for pronunciation, which might look a bit complicated in the beginning. Don't let it put you off, you only need to learn to recognize the symbols used for Gaelic, and not the whole alphabet. It's the only way to get an exact transcription of the sounds.
Fuaimean na Gàidhlig - The Sounds of Gaelic - Here you can fill the IPA symbols with life and listen to MP3s.