They sold for $1.4m with a poor layout.

You know him better, so use your intuition to determine the best way to have this conversation.Silly question, and maybe I am just naive, but don't most contractors bake these admin/reimbursement costs into their total quote?

There are designers who focus on ADU layout, drafters who just draw ADU plans, and contractors who just pump out garage conversions.

You think changing interior design, pictures, layout, etc would change STR success?

There are properties you can find that might already have an ADU or a layout that would allow a unit to be split off with a separate entrance (ex: converted garage). 

I have looked at Quickbooks, and find Quicken for user more user-friendly and intuitive. 

They decided to pass on the house, and are under contract on a different house with a normal layout and a garage.

After I had provided the info, they kept coming back and asking for additional information (at this point requesting I lay out to them what it was I specifically wanted).

@Alex Veytsman I really appreciate the site and layout.

Once you get past the zoning hurdle, its important to engage an architect who can lay out units.