It doesn't seem often, but these people are not the kind you want angry at you, so anything I can do to improve the situation would be good. 

Otherwise, don't mention down payment--if they hold the note, you'll be improving the property with your rehab.Hope you get the drift. 

If you plan to live there for an extended period of time and it would lower your current cost of living that would be an improvement, but this would be a negative cashflow investment and I'd personally pass.

Raising rents, remodeling units as they become vacant, improving common and exterior areas, better maintenance and management than prior ownership provided.

While improving that take on another 2-4 unit you can BRRRR.

Terms are better if you're improving a building for energy efficiency as more lenders want your business.

Private sewer improvements can easily cost $500,000 or more. 

@Chris Moyer This  is a joint-venture or at the very least a promissory note.

Is the project a Class B value-add with minor improvements to reach B+ /A?

Biggest value adds, from what he said, were increasing square footage, and then improving the kitchen and bathrooms.