Zoning allows for medical/dental, construction, and light retail.

The problem is that he has no experience running a "buy/hold" real estate business, so he doesn't necessarily know what to say when it comes to operations and sales.Can any of you shed some light on these aspects of the business model?

That being the case, you need to become an expert on analizing the costs yourself.Here is what I would suggest: Spend many hours at Home Depot and/or Lowes to familiarize yourself with costs on typical rehab items such as flooring (carpet, tile, travertine, etc), toilets, bathroom vanities, sliding mirror doors, interior doors, baseboards, door casings, light fixtures (celing fans, etc) paint costs + paint supplies (tarps, brishes, rollers, etc), windows, sliding glass doors, kitchen cabinets and countertops, sod, trees, plants, bushes, ground cover, etc.

I can shed a lot of light on this deal.

Even if some moron deeply gouges or somehow burns the tile, you can use a belt sander (with a somewhat light touch!)

I have 15 private offices and a 900 sqft hall for hot desking.

As Hurricane Harvey showed, "flood maps" can be unreliable in light of global warming.If a few hundred dollars makes the difference between profit or not, your deal might need to be reconsidered. 

This essentially means you need a lot higher income to qualify for properties as a primary residence while as an investment property the pro is that you get to use rental income to offset your mortgage PITIA and you ONLY have to qualify for whatevers left if the calculation results in a negative cashflow number (if its positive it actually requires zero income or it just helps your situation ).So regarding the topic of how DTI affects what you qualify for, yes DTI is the main determinant that will affect your purchasing power so carefully plan your next 5 moves like PBD patrick bet david says but in this context its the next financial strategic moves not PBD's 5 next moves.Let me know if that helps or questions that arise and someone on our team can help shed some light on this often over looked topic further.

I'm thinking a darker color with a light countertop would look awesome for the money!

There is some mold on the cardboard backing under the side wall (at the bottom of the wall where the medicine cabinet and the light switch are).