Either the toilet is leaking below the floor level or there is degraded caulk/grout surrounding the tub/shower/walls.

It needs everything: all appliances, cabinets, flooring, tiling... everything.

Regardless, my strategy was to live in the basement and rent out the bedrooms on the 2nd floor.

All units have vinyl plank flooring.1% rule would make the listing price 570,000 using my LTR data.

And are potential guests interested in staying at a STR in a basement that can have occasional squeaky floors from time to time?

The top floor has the bedrooms.

Only if you consider working every night, weekend, holiday, and times when I should have been on vacation lucky, mucking around in crawlspaces, hunting down houses, falling through floors, etc. 

Also the majority of those costs to covnert to a 2nd unit will need to be capitalized and depreciated, but some things (new appliances, flooring, paint, kitchen cabinets) can be shorter year assets vs. across the full 27.5 and IF it turns out that unit is > 50% you can use bonus as well on those items.

@Devin James What I am hearing from a lot of buyers is they’re tired of the grey/white combo and personally I can’t stand it as well but I love what you did with the floors, this is a very clean look and I actually like what you did here.

I gutted it and added new drywall, new light fixtures, new bathrooms, new paint, new kitchen, new furniture and new flooring and new windows.