@positonic I'm afraid you'll have to wait for someone else to comment on spark-specific advice, but I can advise on paying users through stripe a little.
Stripe has multiple services, but two can almost be thought of as 'account types' of sorts. You have the normal user which submits payments to the application, but you also have vendors who can be paid through the application, minus a service fee (this is your cut). These vendors are called Connect accounts.
Again, I do not know the specifics on how to do this with spark, but in a normal application you would send a separate api request to create a connect account for anyone getting paid through the application. I am not sure if a Connect account can pay you or not (outside your service fee %), but if not it would just be a matter of a database structure to have one team owner in your app connected to both a normal and connect stripe account.
Stripe themselves explain connect very well, and it works phenomenally. If you're wondering if it is possible, then yes it is, and I am willing to help as I can on Stripe Connect (I am currently building an on-demand app at runnurapp.com which uses what I have described). If you're wondering if it is supported by default with Spark, I can't help you there.
Hope this helps at least a little!