It's not normal to do it prior to an accepted offer.

he is offering to bump his offer from 12 and 15% to 14%and 17%.

It offers unique advantages like equity building, tax benefits (e.g., deductions and depreciation), and an inflation hedge, as rental income and property values often rise with inflation.

MFDUs in high-demand areas like Asheville might be limited, but it’s worth keeping an eye out for smaller duplexes or triplexes that align with your budget.If neither works, continuing to rent while buying a pure investment property in a more affordable nearby market could make sense.

If the place is in decent shape I would offer to credit it toward the next month's rent and write addendum including no future pets.

Understanding your market, what you are offering, and the kind of tenant you can expect to attract and KEEP will help you determine how to screen.

They perhaps can build cheaper than you can, finance cheaper, operate cheaper and to get it leased up, offer things like 1-2-3 months free rent. 

Unfortunately many landlords take the first group they find in these situations and come from the ideology that all college students are slobs so no sense offering anything nice. 

We had a walkthrough which I always offer for obvious damages (ie holes in the wall.).

If everyone uses your tool, and everyone gets the same answer and places the same offer, then no one has any competitive advantage.