We did end up doing more work than we had planned, but ultimately I think the decisions we made added the appropriate value to get the returns we had hoped for. 

I did my homework to make sure it was priced appropriately, had all my ducks in a row, and was able to sell my first home myself after one open house.

I'm currently involved in a different ADU project for a similar property, and that's pretty much where I'm pulling my numbers from for construction costs.Again, my overall question is, are my home insurance figures / earthquake insurance figures / property tax calculations appropriate assumptions?

If your numbers still work and you are able to get an appropriate profit, good for you!

I think a certified letter is appropriate and cite the laws the tenants are violating and the sections of the leases.

As such that information must be appropriately guarded at all times.

Make sure you are putting in annual and monthly values where appropriate. 

I wasn't managing the property any more but helped the owner secure the appropriate contractors before he even asked for help (he was out of state).

Are they appropriate questions to ask the current owner of the property?

We have an up-front review/question about what amount of investor involvement is needed to make this an exempt offering (I think that’s the right term) and then we’ll need to move forward with executing the appropriate paperwork.