In Nevada for instance, the state requires a real estate license and a property management permit in order to manage property for others.  

If repaired well with permits closed out and all, an old fire shouldn't affect your insurance or financing options. 

The job has to be permitted and inspected by the city/county inspector, so the short answer is "YES." 

Land acquisition, permits, foundation, utilities, architect, and on and on but without the additional benefit of profit on the larger sq/ft you'd be selling.

Be prepared to potentially have zero income for many months.In addition, you will want to check the permits.  

Some grandfather in existing units but make owners go through a permit system.

You'll need a permit and maybe some drawings (?).

If your area permits top market rents, you might opt for the fancier appliances if directly competing with other landlords for the creme de la creme tenantsLaminate or granite countertops?

Then if the LL agrees to the LOI terms you’d draft the official lease agreement that includes all of those terms for due diligence, feasibility, permitting, construction, rent commencement date, etc. 

You'll find some heavy hesitation on most lenders if it hasn't been planned/permitted because of the delays that those things are prone to have.