@Casey HuntSpend a few days removing most of the grout between the ceramic tiles with a grout removal blade on an oscillating tool.

The only thing that works is a 4 inch razor blade on a 12 to 14 inch handle. 

If there is/was little insulation in the attic (the ceiling joists are exposed above the insulation), you would have cooler/warmer temperature along the bottom of the joists which could both cause moisture issues and may have affected how the smoke particulate stuck to the ceiling.If you take the pointed tip of a knife or {one blade} of a pair of scissors and {gently} press into the drywall along one of those lines, is the drywall hard or does the knife tip slid in fairly easily?  

I agree on all your points.Being new to real estate can also be like giving 5 year old matches or razor blades to play with; you can cause unintentional consequences if you don't know what you're doing. 

As someone wise said, "When life throws a dagger at you, you can catch it by the blade or you can catch it by the handle."

I spray kilzed the entire inside of garage,, the roof joists, studs, and anything I could see.The garage floor was the biggest challenge.. cement,, crystallized cat pee in layers.. no joke, I first tried a garden hoe to scrape it off,, nope,, then a 4" razor blade long handled tool for removing vinyl tile or popcorn ceilings and that got most of it up.. 

The fan most likely needs to be balanced which is a simple process where you have to add little weights to some of the blades, this happens over time as the house settles so it can just pop up whenever.

I bought a few packs of sawzall pruning blades and a cheap electric chainsaw from Harbor Freight (After ripping the cord out of my trusty gas powered first thing that morning.)Me and my helper went to work.

I go to Harbor Freight for hand tools and blades. 

I pointed out to him that in the medicine cabinet, was a little slot where people of the time would literally drop their used razor blades right down into the wall.