Hi Sweet, welcome to the board
Yes, mostly STalthough you can take them LT for a prohibitive barfine. You have to pay for both the room and girl, normally around 200thb for the room and the girls will want around 700thb but as always it's negotiable.
Even if you don't drink it's worth grabbing a soft drink or 2 downstairs to check the girls out as you can have a real laugh in there whilst also working out whether the girl you're with is going to be all that when you head upstairs. There's so much choice on the soi that, especially if you're new to the place, it's worth checking out what's on offer before you head up to one of the rooms.