He received quotes to remove the texture ceiling, paint the interior, purchase and install new kitchen cabinets and counters (including completing the design), picked out 2 floorings to get quotes which will be provided this week, and determined furnace is beyond saving (I will likely get HVAC quote for him).  

I usually recommend clients a pretty easy cosmetic rehab which is refinish floors, replace cabinets with modern white ones, add a white stone, new appliances, new bathroom vanity/mirror/light fixture and add in unit laundry. 

Granite or Quartz on all counter tops including bathrooms.. our up stairs is 9 foot.. and our single levels are 10 foot to 14 foot which NO other builder does in a subdivision type build only custom homes over 1 mil would have that.. flooring is engineered hard wood.. custom cabinets with soft close on all doors in the house..

And they had taken the kitchen cabinets apart and burned them in the fireplace for heat.....I salvaged some and painted over the burn marks, didn't look half bad....ya can't make it up, right?

Baseboards, couch cushions, above fridge, in cabinets, grout/caulk lines, rug maintenance, air filters, windows inside and out, dust the top corners of windows, corners of high places etc etc.  

Imagine what our grandparents paid for TVs relative to their income, for a 12" BW box inside a cabinet that weighed 300 pounds, especially in today dollars . .. . 

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.

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

Said I wasn't allowed to have a glass window in my old back door. so I covered it in cabinet grade plywood and trimmed it out to make it look as good as possible.

Important things to check include opening and closing every cabinet, looking under sinks, pushing on doors and cabinets, and checking commonly used areas.