Budget is $200,000 and I plan to put down 20% that is a gift from my mother.I talked to a mortgage broker with Edge Home Finance and submitted an application for pre-approval.

It depends what you long term goals are?

My thinking- many ppl escape Florida now bc of taxes and insurance cost.

Excel tells me how much all of the regular things are (mortgage, insurance, etc), but the notebook is where I track everything for taxes and what I grab when I do my taxes (along with a file with all the receipts and copies of bills). 

If you want to get a great agent, you want to be able to tell them that you are pre-approved (and for how much, for single- or multi-family), have confirmed hard money if you are going to flip, and how much savings you have.

Current Loan Balance: 100,952Interest rate: 3.75Mortgage payment + insurance/taxes: $1066Rent: $1500/monthEstimated current value: 227k Current cashflow: $369/ month, I also have a first american home warranty on it $68/month so after everything I net about $300/ month. 

Which are more prevalent in Santa Fe single family properties: pre existing ADU's or a potential to add ADU?

In 3-4 years, you will not have a lot of equity in the home, so I'm not sure you'd want to refinance (if you plan on trying that, talk the bank because ending your mortgage before the term is up (ie 1 yr, 2 yr) comes with a heavy interest penalty (basically you have to pay out all of the interest remaining for the rest of that term).As for renting vs investing elsewhere-run the numbers as to what your payments would be if you bought a house including insurance and property taxes and repairs vs renting. 

Whoever is doing your property management on this rental should be able to advise you on what to do with a pre-existing tenant and what rights they have to the property.  

Depending on income and credit there are always credit card, personal line of credit and personal loan options available out there