I just read a WSJ report citing Bankrate a banking analyst, that 3 out of 5 Americans do not have the reserves to withstand the most mundane unexpected expenditure, "The survey found that an unexpected bill would reduce spending elsewhere, while 16% would borrow from family or friends and 12% would put expenses on a credit card. 

You forgot maintenance, vacancy, capital expenditures in your pricing model.

If you are confident the property once rented will be able to cover your mortgage, insurance, taxes, maintenance/repairs, and capital expenditures, then renting out the property is great.

The 109@ will be for "gross proceeds", not net income.......so however you agree to split the gross, after considering your partner's rehab expenditure.

I would also want to know current condition, any deferred maintenance, any recent CapEx expenditures, copies of leases, etc.

A couple of things are not stated so we don't know, but are you ready for any capital expenditures that are bound to come up (roof, heat AC, etc) and can you live on the current cash flow or are you doing a 9-5 as well?

In retrospect, simply having held the initial property without any remodel or investment would have yielded far greater returns with little to no energy expenditure. 

And, just last month, they had an unexpected expenditure:"December 2022: The CFPB orders Wells Fargo to pay $1.7 billion in fines and $2 billion in consumer redress in connection with "illegal activity" across several of its product lines."

I'm starting to look at places to analyze but I'm not sure how to calculate repair costs and capital expenditures

However, any growing rental market is likely to also have a corresponding growth in property managers.With any turnkey operation you should be able to get a report from them on the rehab work done so you can at least assess what your likely  near-term CapEx expenditures might be and when.