This wall essentially creates a demising wall for the second half of the garage where there is a kitchenette, gas, water heater, shower, and toilet installed however, no interior framing was ever done and it just looks like a dilapidated apartment.

what's there to say, you have great pics, great reviews and take care of things as you get complaints if there reasonable(flaky pans). we all get stupid complaints like the fridge but overall looks pretty great. we have two beachhouses and have 5 and 4.97, the only thing i would even remotley critcize is the perceived value. for some reason your guest are viewing it as not a good of value as they would have thought- although that is a VERY small item as your overall is 4.94 and i suspect your decently full so keep rates where they are and enjoy.Looks great!

Who's dealing with late rents, unauthorized animals, unauthorized occupants, clogged toilet at 11pm on a Sunday, etc.

The sewer lines have already been placed, inspected and concrete poured so I cannot change the location of the toilet or tub. 

I'd definitely say you need to plan on additional expenses upfront such as: permitting fees, extra holding time if there are permitting issues, all the little things in the drawers and kitchen etc, hot tub, amenities such as toilet paper, spices, laundry detergent, dish soap, shampoo and conditioner etc. - stuff you need to restock and have on hand.

No toilets to deal with, no tenants, no leaky roofs.

They can only get the big bucks for new fixture counts, so having that info handy should get you an assumption of at least 12 fixtures. (5 toilets, 5 bathroom sinks, and 2 kitchen sinks (two units permitted))Something to help you back trace, it is possible you might be able to get a mechanical permit number from the utility for the gas meters, and see if that permit number is associate with a building/structural permit with the city. 

No leaking from the toilet.

Living/ DiningKitchen/ Pass-through WindowBathroom(Moved the toilet to add a laundry space)Bedroom 1

New toilet, sink, flooring.Bedroom: Paint, flooring, and remove weird shelving.Living Room: Paint and vinyl plank over the old wood is the plan.The exterior of the house.