Be sure that whatever structure you decide is best for you that you also understand how your business will operate to ensure that the structure or corporate veil is preserved.

With no experience in STRs yet, I’d say give yourself the best chance to win by ensuring you have enough capital to buy and invest in a property that guests will want to pay you more than everyone else for because of those decisions you made on timing and acquisition.my two cents!

I am not aware of any tools anywhere close to as efficient and easy to use as the CMA tools available to me now, as an agent.

Just as efficient as mask-to-mask if not more, and saves travel time and gas. 

Is bigger a higher ROI and more efficient?

I intend on managing the property myself under the LLC, but want to ensure I dot my I's and cross my T's by hiring an accountant.

Using a portion of your house is probably the most cost efficient way to operate a STR, though nor for everybody.

What would be some ways of ensuring a broker or realtor is investor friendly?

You can only push rents so far so you need to buy right and increase operational efficiencies to maximize income on smaller properties or get into larger properties with more income. 

Im in houston texas and would like to know what performance metrics should I seek in a 1 to 4 unit home to ensure Ill get approved for another loan year after year?