I've done several buy/sell with owner financing, but never with a non US seller/owner. 

Assume you'll hear that the house is worth it when it isn't, tenants are good, management will handle everything, it will be easy for you, vacancy and non-payment will not be much of an issue, repairs won't cost that much.Some will be honest, some won't. 

Any experts out there with some insights on non-conforming, grandfathered, weird properties...that might not have similar comps, hence making it harder to find a loan, etc?

Does each one get any public transportation and bus stop locations. 

Simply put, historic registered buildings generally have no more value as an investment than non listed buildings. 

Using the QRP oans get you the second tier financing options, for example, a Roth IRA can buy real estate on leverage, however, will need a non-recourse loan which is often a fraction high-interest rate and lower LTV.

It seems like the places with high public development are getting hammered with property tax increases.

Loan docs are usually a deed, promissory note, deed of trust, lender's instructions to the title company, and attorney letter of non-representation. 

I see UTC as both a draw to the youth and retirees since one is able to take public transportation to employment centers of Sorrento Valley, the entertainment of the UTC Mall, get to Petco Park, Old Town, Downtown San Diego Mission Valley.

I either sell them on a land contract or do a lease option because I get more money upfront, the money I get is non-refundable (unlike a security deposit), the occupant takes better care of the place, and if I get the property back, I get to repeat the process and make more money off the property than I would as a rental.