In the end you guys would no doubt use a lawyer to draw up the contract so all parties are protected, don’t worry about that part as it comes later.

The deal is making me somewhat schizophrenic as one day I think it's a good deal and then Im blasted with doubt, but I've been fervently running the numbers all different ways for the past week.

It took me 6 weeks to find her (because the rent is high--that's a long time in my area) so it probably won't rent quickly if she leaves, plus I doubt I'll find someone else who keeps the property like she does.  

I won't say it's impossible to do multifamily/passive-income in CA, I just doubt "I" can.I've got no real estate experience, lifetime renter, so I've got a lot of learning to do and I'm looking for a market with enough cash flow/cheap enough that I can afford to make some mistakes.

I doubt there is the inventory in your area, and you may have to end up moving closer to the city to find what you are looking for. 

I use 12% for all of my own projections.I think Roofstock is doing a great job overall and if I found the right property I would no doubt use their platform, but my point is be sure to do your own research and vetting on the homes and neighborhoods, and try to use your own #'s when determining cash flows, etc.

I highly doubt you have to lend as an individual.

I doubt you will break even unless you have a large down payment.

I seriously doubt anyone literally just sees a positive cashflow and buys without any additional thought to location or the possibility of changes in future revenues, nor have I ever heard any BP contributor or employee suggest such a thing.

When in doubt get an appraiser.