Contracts just say I x agree to pay n dollars per t time for work. That both sign. And then sometimes have clauses if party 1 or 2 doesn't pay or do the work.

You have two options imo (probaby...ianal,...), give a contract that has rate on it and then your timesheet, or just contract and invoice them after.

You can do a simple contract off google.

Just do 1 Job at a time imo