Probably a good price comparison.Please define "gut".  

I am still working on my characterization of each surrounding area to define which neighborhoods are growth and which ones lack rentals (and thus need me to place a few).

If you have a central system that is an integral component of the structure, then the system is depreciated on a 27.5 year schedule, just as you would depreciate any new structural component of the dwelling structure (e.g., a new roof).

Define income?

You can have a weighted average approach, defined by various considerations, and have expectations generally obtained for that type or property, in that geographic are, under expected economic conditions assuming prudent management taking into consideration property condition, age of a property, it's location and known variables.

You need to define the nature of your business and then sit down with a good insurance broker who can write the coverage that will match your specific areas of risk.It's important that you find a quality, knowledgeable broker.

They have been a key component of me wrapping my head around this thing and getting a plan in order.

Having a sustainable business with a mainly flip only component in market cycles over time will be tough.

The question should be "As a business what would be the most effective use of my disposable capital in order to grow my business as quickly as possible"  Specifically defining the goals and needs of your business really helps you stay on track and focus on the fundamentals of fast growth.  

The garage door is an integral component of the rental dwelling structure and as such its replacement cost would be depreciated over 27.5 years.