That sounds fair, thanks. Expenses would be gas for car and/or other transportation. It does seem odd that my band members have not mentioned expenses they've incurred in driving to venues to talk to owners about gigs.
No booking agent at this point.
And also odd they feel it's *their job* to find the gigs.
The expenses that come to mind are gas, printing costs for posters, and any sort of online ads (which I do NOT recommend for local gigs.) If the money is good enough, I don't even bother with expenses; I can just claim that on my taxes.
You're the drummer. I've never expected the drummer to incur any expenses or effort to book gigs. In fact, I can only think of one instance in my entire career when the drummer booked a gig. A bowling alley that was across the street from our rehearsal studio; we played there once a month for a couple of years.
The thing is, even when everyone else is doing their bit, and helping with load-in and load-out, you've got a very complex instrument to set up, and perhaps even tune on the spot. That's more than enough extra effort. And, you're literally the core of the band. I've performed without various players due to whatever, but no drummer? Never. That's a solo performance.
I don't think it's fair to ask the drummer to take on more responsibility than they've already got.
Really, the best person to deal with booking and payment is the singer, as a general rule. I've served as backup/reassurance to singers when I've worked as a sideman (guitarist), but they're the face of the act, and that's a natural part of their role, to interface with the venue and the audience. So, in my view, it really is "their job" to find the gigs and promote them.
EDIT: Yes, it is customary to get paid after the bar settles the till, whether you're playing for a flat fee, or a percentage.