Next time on a MAJOR renovation project, I'd have the City of Johnson City Building Inspector join me for a pre-purchase tour to tell me what permits and what jobs they'll require of me.

I believe that would include permitting USPS to forward the letter.As already stated, if you can't reach them with your letter, then you won't be able to serve them a summons for a court hearing.Chalk it up as a loss and move on.

If you need a permit for it, some things can be permitted retroactively.

To answer some of your other questions in general about Huntsville, there are almost no basements here, and you never want a pool for a rental unless its an STR, which are now forbidden here without proper zoning and permitting.  

Grading/ sewer/ septic/ permitting /any subwalls ..  

@Caleb Christopher I heard that KCMO requires a rental permit... would you know if that true ?

Political threads are not permitted on BiggerPockets.

Could this be a DIY kind of thing, If so is there any permits or code violations i should be aware of?

Next time on a MAJOR renovation project, I'd have the City of Johnson City Building Inspector join me for a pre-purchase tour to tell me what permits and what jobs they'll require of me.

Please note, units have to be registered (then renewal annually) with the Department of Planning and Permitting in order to be operated as legal vacation rentals.