This will minimize the tax burden of the gain you currently have and defers any other gain through the 1031 giving you more buying power going into the future.

Since most of the homes that flooded took on electrical damage, you will almost certainly need to file a permit to do renovation as you will need the electric company to shut the power off, provide temporary meters, and turn the power back on.

Running detailed cash flow projections, factoring in their management fees and expected rent increases (you can use some of the great BiggerPockets Pro tools like the calculators to do this!)

CoC is an, all things being equal, comparison tool between properties.

RE's super power is equity over time.

You cannot beat the power of an ADU for peace of mind, leveraging your home to pay less monthly and reduce your expenses and give you the experience and confidence of doing constriction, getting permits and working with the city and managing a very easy rental.

The power plant near there helps quite a bit.

What tools or processes have you implemented to estimate rehab costs more accurately and avoid scope creep in BRRRR projects?

Use tools like MLS, Redfin, BiggerPockets calculators, and Zillow for cost and income estimates, and enhance research through networking.

I'm using a combination of MLS comps provided by realtor, redfin, and backflip analysis tool.