Do they serve other drinks then just beer here? What is good time to show up on Saturday with a big crowd

It gets crowded pretty quickly, especially over the weekends so I would suggest, the sooner, the better. You can order off the menu but as their speciality is beer, you might not get more options in other drinks

Yes they have some house cocktails and I believe some wine. If you have 6+ or so, call ahead to see if you can get an outside table reserved