Im the Sales and Production Manager for a roofing company (Fixler). 

@Sam Rane My answer to all 6 of your questions is: it depends.Many of your questions are addressed in two of my favorite real estate books, both authored by the legendary @david greene.

What exactly this loan product will look like, I'm not sure. 

In addition, that 30 year product has an interest only option in the first 10 years to maximize cash flow.

I think usually your best bet is to use 1/4 plywood underlayment and/or some sort of leveling product to fill in low spots along with some method of grinding high spots (primarily you need to get the floor FLAT, not necessarily perfectly level.

Go find expensive houses that have sold in the condition you want to rehab them into (something like the end product you envision) and then see what they would rent for.

Not familiar with this product. 

@Dallin HernandezWelcome to BiggerpocketsMost lenders, conventional or portfolio, will require 6 months on title and for the property to be stabilized before you can refinance it into a long term loan product. 

Usually there is not a ton of equity built in on this loan product.

Because you won't have issues with lead paint and asbestos as both of those products weren't really used in residential applications after about 1978.