If the property is paid in cash and later a mortgage is secured does it impact the UBIT question above ?    

It sounds like a smart way to build equity and stay secure financially.

I’d appreciate some feedback on my current approach and advice if any.Here’s what I’ve done so far:Pre-Approval: I’ve secured a pre-approval amount and interest rate from an online mortgage lender.Property Analysis: I’m using the mortgage and STR calculators from BiggerPockets to assess the financials for potential properties.Neighborhood Research: I’ve been exploring different neighborhoods using Niche to get insights into schools, safety, and livability.AirDNA: I’m considering subscribing to AirDNA for data on occupancy rates and rental income estimates.Questions:Is AirDNA worth the investment for STR data?

The following is in my purchase agreement and I alway get a MOC on all purchases  MEMORANDUM OF CONTRACT RECORDABLE, PERSONS BOUND AND NOTICE: Buyer may cause to be recorded, at Buyer's option and expense, in the public records of the county in which the property is located, an executed Memorandum of Contract.

I would want my money to be secured by a promissory note and mortgage on the property in question, and thanks to the advice from some on here, if the property in question isn't enough to cover it, I would need to attach a lien to other property to ensure I can get my money back. 

Have all your ducks in a row so you can move quickly on securing the deal when you do find the right one that the numbers work on.

The security deposit was $1,200, but here in Florida, attorney's fees and costs are recoverable to the prevailing party in cases concerning security deposits.

Security deposit amountYou can find plenty of examples by searching for "tenant estoppel certificate doc" or exchanging "doc" with "pdf" for more options.Here is an example and explanation: Sample EstoppelSome have a lot of legal jargon but this document does not need to be so detailed.

He sent me a contract which if I sign will pay him a fee of 3% of the money secured. 

for sure that is always an option, right now i want to connect with more actual private lenders that want to move their capital at 11% secured by real estate