If option 3 is not your choice, how are you running your properties and what methods are you using?

Once you've been to 6-10 meetups and you only focus on building relationships without asking for a mentor, you will have plenty of options, especially if you are willing put your skills out there to help them.

I would love hearing your thoughts and experiences in how to negotiate and what are the best options to sweeten the pot in a SF deal.  

You can explore other options when you have it to increase rents.

The owner financed position is a potentially zero interest loan that should be considered.Another quick note: consider leasing his land with an option agreement as well.

This is why I say it may be limiting for you because you won't have that option. 

I'm seeking guidance on where to start when it comes to understanding terminology and what my options for investments even are.

Lot of different financing options depending on what you're trying to build!

My other option is to pay off the balance on one of our mortgages and cashflow more. 

The loan programs for 1-4 units have more favorable terms depending on if you're buying with income with a conventional investment property loan or having the loan underwritten by the rents with a DSCR / rental property loan. 5-8 loans generally have tougher underwriting and the rates are higher if you're looking at DSCR loan options for 5-8 units.