Just like other bars, you order and pay at the counter. They do accept EFTPOS. They don't offer water - if you want a drink, you have to buy it at the bar.
The food there is somewhat average, so it is best to leave it to just the drinks. I had a pizza for $12.50, which had cheese and very little toppings, but I once had their burger specials and they were yummy. I didn't really like the chips much, but I loved the veggie burger. Yum.
In short: come here for the burgers and drinks and not much else. Also be prepared to talk really loudly.