2 - It can be phrased as a question, statement, or suggestion. You can agree to something by saying tumbat/tum, or use tumbat/tum to phrase a question, IE: if you hold up a beer and say "tumbat/tum?" you are asking if they want the beer, the person can then use tumbat/tum as a positive response meaning they want the beer.
3 - tumbat can mean a variety of different things depending on how you use it, IE: in the last above situation stated, "tumbat" could mean "cheers" or "drink" you got the idea if yous really tum...so get creative tumbat!
2 - do you wanna get some food/ i wanna get some food - "tumbat/tum gettin some food", or "im tumbat/tum gettin some food"