Just shoot me an email and I'll provide you contacts to a great landlord attorney, investor friendly CPA, and also the necessary steps for leasing to the new tenants, as well as the renewal of the current tenant if/when that has not been completed yet.

the answers to all of your questions are... go find those people in person, which is difficult to do out of state unless you're traveling frequently to your chosen market. 

Even being in a tenant friendly area, it sounds like you have several valid reasons to not renew this lease.

I was asked yesterday by a good friend of mine who has got 1-2 rentals in the last year and I wanted to check with you all first.

I have frequently contacted sellers about properties that are off market that I feel pretty strongly that my buyer would be interested in or they have contacted me about. 

There are turnkey companies or platforms like Roofstock that assist investors in doing so or you can contact property management companies or look for investor friendly real estate agents in that market to assist you.  

The kids can always go to a friend's house while you're there.I'd also look at when her lease is up for renewal and tell her you are not renewing her lease and she needs to find another place to live.

I’m looking to team up with two friends who are eager to move out of their parents’ homes.

Take advantage of the need to get new residents more frequently than an LTR by experimenting right after you've filled a listing: change up the description on your platforms, try a new platform, raise the proposed rents, or practice reaching out to those "bad leads" of FF.

San Diego and the surrounding areas are VERY ADU friendly so there are properties with options to add one in the back that are really starting to pop there and could be an alternative option.Take it slow.