Discuss plan with Planning Zoning group.3.  

You'd need to start working through a preliminary site-plan to validate your assumptions about the building area, parking ratio, drive-thrus etc.

All new flooring, bathroom remodel, paint and drywall in the bedrooms.

I do condo plans as part of my W2, and these SF calculations can vary based on the coord with the attorney and owner as far as how the association is originally set up in its budgeting for dues.

I plan to use two of the bedrooms for Airbnb short-term rentals.

No contracts and you can transfer your cameras from project to project.Depending on how much coverage you need they have really low monthly plans.

Plans for what you're building will be key - it's too vague and open right now for someone to advise you on potential cost. 

Re-titling real estate can get expensive with the misc. transactional fees associated with the process + you are at risk of the lender triggering the due on sale clause if you don't plan on refinancing the real estate.

Good specifics - thanks.3 story "walk up" - like a unit on each floor?

@Alina TrigubA Solo 401(k) does not eliminate UBTI generated when the plan engages in a trade or business.