Don't want to give out false information but I am in a similar situation right now and am curious how it is going to work in the coming years.

The big thing your friend probably wants is that it is your contact information that prospective tenants see when they reach out.A general tip beyond the usual blackout curtains, nice bed and safe area, would be that we've seen that most of our bookings come within days of a lease expiring. 

That is something you should get detailed information on before proceeding. 

We have focus groups for mulit-family, flipping, landlording, and others where you can learn a lot of valuable information and network with other local investors.

Does anyone have a bit of information on what rates I can expect to pay for CA capital gains?

The hard point with an adaptive reuse is when you need to incorporate the appropriate staff for the extended stay hotel angle you need the property setup (reservation desk, offices, etc...), additionally there is a marketing aspect to target the people who would be utilizing the short term stay yet longer than you would with a traditional extended stay hotel. 

I find tenant screening strategy to be enormously valuable information.

I have a STR in that area and I would be happy to assist you with information. 

I have also reached out to some of the real estate companies for information on insurance fees and rental company costs that go into the monthly operations of apartment buildings.

You’ll find lots of information, networking and education and maybe even someone willing to mentor you.