If I was renting out the other quarter acre I’m using, I’d have over a 100% return in the first year.

If so you would likely need to pay the estimated repairs out of pocket and it would increase your cash down for looking at cash on cash return. 

Or would it make sense to take our return and dump it back into another deal and pay ourselves a flat amount?

In a phrase, they buy for return OF investment, not return ON investment. 

It will be next Wednesday at the Starbucks at 5800 West Memorial.

Here in FLorida, in the 2010-2015, I sold almost exclusively SF investor homes (about 200 of them, to investors from Cali, and abroad), and as values rose, and ROI's dropped, I found the natural progression was toward multi, to get worthwhile returns for my clients. 

On average, what kind of Cash-on-Cash return can you expect in the Spokane area and what cash flow per-unit per-month should I be aiming for? 

Definitely seek the services of a reputable attorney who can memorialize the economic agreement between you and your partner. 

I underwrote the deal at a 25% IRR which is a crazy return. 

I would strongly recommend you look at downtown San Antonio, or submarkets around San Antonio/ Austin.I have found the returns to consistently be far better.