Hi Kristin. Congratulations! You’re absolutely correct, this is a HUGE open-ended question! 🙂 There are so many considerations here. For example, you use the term “employee” here, but is this really the arrangement that you guys are working towards, or will you be an independent contractor (which is what your question actually implies from words such as “join on with a fellow coach,” and “how to handle finances.”)? Handling finances to me indicates that you guys are considering an independent contractor arrangement – is this correct? Charges for services, fee-split arrangements, liability insurance coverages, marketing, facility access, and who receives client payments are all just A FEW of the many details you guys may need to consider.
I would highly recommend your getting together, and each outlining how you see the arrangement working. Then, spend an hour or so with an experienced business attorney (preferably one with experience working with fitness clients) to memorialize your agreement/arrangement on paper.
I hope that this helps.