.- Using an attorney for a real estate transaction and mortgage structuring has been so easy and very cost effective.- Offering the seller more than they thought their home was worth made them willing to finance the home for 0%.Bottom Line - 1. 

I also learned lenders can be very selective with these types of properties. 

Would this negatively effect the property in the long run with it being built in 1910?

This would effectively end the ability for accredited or sophisticated investors of using IRA funds to invest in private syndications.

Any other advice on HVAC selection?

@Gail K. https://www.zerohedge.com/covid-19/ends-debate-israeli-study-shows-natural-immunity-13x-more-effective-vaccines-stopping(Cliff notes in article.

I looked into them briefly for a unit that I was considering a traditional STR until next July and then 30+ day rental after that (when San Diego's STR quota goes into effect). 

While the current lifetime exemption is approx $ 11.7M, this is set to be cut in half effective 1/1/26, and that reduction may further be accelerated if tax legislation gets passed.

If it's a basically functional and complete home, and you will have a bunch of equity, a cash out refi or HELOC would be significantly more cost effective (rates/fees) and easy (paperwork, back and forth, closing time, etc) than a renovation loan. 

What do you feel is a 'good' ratio of home owners to tenants, and how does this statistic really effect a certain area?