I am thinking about just finding some templates online but not sure if there's a better way to go about it.

Build Your Buyer’s ListNetwork with Local Investors: Join online real estate groups, forums, and local real estate investing associations (REIAs) to find investors in your target markets.

Some of their products have a toxic smell so you have to be wary of that, especially if you have animals around neither you nor them can be exposed to it.Meaning you might want to test paint a room and see if that solves your problem.Good Luck!

Stop looking online and find an investor-friendly agent in your target area.

Join local meetings, attend real estate seminars and workshops, participate in online communities, and network with local real estate agents.

What are good strategies or online calculators to help make rehab estimates? 

Although, the likelihood of this and enforcing it if not honored is a whole 'nother animal.

Is the courthouse the the only solution, or are the records readily available online?

I do believe that, because of technology (on line deed information and ability to filter such) and higher interest rates, we will see more acceleration of loans due to due on sale violations than in the past.  

Go online to Airbnb in Avondale and reach out to some of the "hosts" to get the answers.