First of all I'm not a lounge owner but I will add my dime.
My tip on the business: Since it depends on what tobacco and amount of heat you're using I'm really betting you'll have to experiment with it. Preferably several times with each combination. In any event I'd recommend you do your best to find out what bowl you'll be using and perhaps (I don't know your business plan) mass ordering?
My input as a consumer:
At the lounge I went to in Tampa, sessions would last about 45 minutes with the tobacco they packed. In the one in LA I went to, it would last about twice that.
I remember you're having a more modern lounge with the automation and I thought that was an absolutely brilliant idea!
Perhaps you could have them punch in if they want a shorter or longer session? (You could even charge accordingly.)
Anyways I know when I'm at a hookah bar I want to try a bunch of things I've never smoked, but that said, I'm sure many would just want a nice session with their favorite tobacco.
Don't forget your customers will likely constantly want their tobacco changed when they don't like it... Definitely train your servers to ask each party to tell if they don't like what they're smoking imo.
I hope I helped.