I will have a sizable portfolio of SFH eventually and we a solid foundation to work from. 

You are correct that holding the property in your name opens you up to liability which includes holding the property in an LLC that is not anonymous.What structure you want to hold this in which also affects your tax & protection benefits, will depend on your relationship to the other owners, how long you wish to hold the property, where you all live, where the property is located, among other situations (i.e. will this tie into anyone's estate, will the property be sold eventually or is a 1031 exchange the best option, etc.) * I am not an attorney and I'm not YOUR attorney.  

It is currently 4bed 1bath and goal is converting to 2 unit by adding a bathroom.

The tenants also complain about the building being on one thermostat.I am wondering if I should replace the two sections of the boiler for $10K and try to salvage the steam heat system, or if I should immediately convert to another system.

You'll build up a pipeline of folks to keep following up with who will eventually become buyer, seller, and/or investor clients.Best of luck to you moving forward!

Also do the math if you convert from vacation rental to long term primary residence rental.

See if you can find larger ones with higher room counts, where you could convert things like dining rooms into bedrooms.

So again, if the CA property is an investment property he could 1031 out of CA and into a number of other investment properties including a condo that he would continue to use as investment for a period of time and then he could convert it into his primary and move in. 

We’ve owned one of the home since 2013 but lived in it till 10/2018 didn’t convert it to a rental until last month of 2019 and the other we purchased in 08 of 2018 and converted it to a rental last month of 2019.

Eventually I just decided that it would be open to anyone that wanted to come.