Only been to K-Pressure and recommend it but to answer your questions.
Yes, you can choose, generally review one at a time.
Price is set, $390 for the girl and $120 for the room. The room is upstairs, the girl takes you up. You pay the $120 to the attendant, go to room. If you want to tip give it to the girl before you leave the room as as soon as you get downstairs she disappears at the doorway.
Don't think they are listed on DB. Generally the girls are not the greatest lookers but OK. They are generally fit too and early mid 30's. Good service though.
If you want a threesome ask the girl on arrival if possible. You pay for 45 min intervals. Never asked about the multiple shots. It can involve multiple shots but it's a bit quick if you ask me to get two off in that time. You can get the girl to give you extra attention while in the room for extra tips.
Ask the girl if she does CIM or anal. Generally they won't offer those services but CIM I achieved last time I was there.
Just get yourself there and give it a try.