However, if I buy a second rental home in  Indiana  ( so I own 3 total) could I potentially be required to comply with the Prop 15 rent control on my California home if Prop 15 passes? 

You may be able to find a bank that would hold the mortgage and not be worried about complying with underwriting rules.

My guess is that within the next decade or two all new construction - commercial and residential - will have to comply with "green" standards. 

Turns out that it worked to my benefit after I demanded they comply with my request.

Then notify the city that you fully intend to comply with their request but that you currently have unauthorized persons residing in the unit and that a Notice To Quit has been issued to the lease holders.Manage to the lease always and quickly...things can go real bad real fast when you don't. 

I also live in a city that doesn't attach unpaid water bills to the property.Unrelated to the water, I ended up having to evict her because she did not comply with my 30-Day Notice to Vacate. 

In that case, you need to consult an attorney to ensure you comply with the state law and your governing docs.

Not being evicted bc of losing job as  a result of covid, is different than refusing to comply with new month to month lease parameters 

Tell her she has to remove all her stuff to get the deposit back in full, then give it to her when she complies. 

It formalizes what you told her and if she fails to comply, you can offset her security deposit for damages and evict her.