We have a property there that we are in process of converting to a STR.

These are some of the items in addition to what you listed that I would be interested in during the due diligence process.

Though, this process will be the same for the other state (if you created a CA LLC you may need to register it as a foreign LLC in the state in which you are doing business/holding property).

When I do it for me and my clients, we go very conservative to give better expectations of the transition process, than if it goes better, great!

In retrospect I would have spelled out the construction process more clearly in writing ahead of time.In your case the existing tenant is getting no new value so there is nothing for them to gain with this project.

Its important to have a smart realtor that can help you through the process and fight on your behalf.

I'm happy to help walk you through the process if you want. 

He wants to help me out and walk me through this process and give me a good property.

The heavy cleaning and repair costs after longer stays are definitely pain points but I've seen my clients make it work by screening the tenants more carefully for MTRs, doing bi-monthly checks to catch issues early, and writing clear lease terms about maintaining the property.

People are imperfect and things like late payers is something you deal with in your approach to managing properties more-so than in the vetting process because if tenants were perfect most would be owners not renters.