Make sure your buy with appraisal and with a third party for advice.

I suggest you contact an attorney immediately.It is possible you are being set for an expensive shakedown for unnecessary monies by  professional  tenants.

This is not meant to be insulting but given the above question on how to fill out a PA, I would strongly encourage you to get some professional help involved while you learn.  

I'm the party doing the owner financing.

My goal is to speak with a few more professionals in different fields related to multi family properties specifically.

If you are an investor, LL, real estate professional, contractor, painter, maintenance person, or at all interested in Northwest Indiana real estate, join on in for discussions.

Tax implications can always be mitigated by a good tax professional.

I agree, you need an attorney and a tax professional on board with you.

Either invest elsewhere where properties are much less expensive or partner with someone and do a 50/50 deal where each party owns half of the property.

Instead, think respectful and professional interactions, open and honest communication, prompt response to tenant needs, establishment of good property management systems, and customer service.