I haven't been for a massage yet...I got my rocks off at Prime instead over the weekend.
From the pictures on their web site, they have massage tables only...but not sure as i didn't discuss this point when I was there looking at the boys.
As this is a sex massage place (my rating, not theirs), I am sure the gentlemen will operate naked. I did not hear or see anything that suggested a minimum tip, but of course the lads will have a minimum expectation I would assume. Just give them Bht5,000 and take back Bht1,000 notes one by one until the guy growls.