As far as money, I would insist on some mock job reports, extend it out into a year's business, and compare to what you'd make on your own.
Suppose they want to give you 0.5% of remaing after cost of goods (after materials and labor)
Run the numbers on some jobs they have in mind:
Suppose they figure 23 jobs, average $115,000
You're looking at $2.6 million
Consider materials, etc at 25%
Labor at 30%
You're at $1.7 million x .05 = $85,000 for you
I don't know what their pitch to you looks like, but you should be able to get some brass tacks projections so you can compare to what you make already
One thing you can be sure of, they aren't looking to make you head honcho