Rules vary from jurisdiction to jurisdiction. 

My brother and I are brand new to real estate investing but have already renovated two of the houses, with varying success.

What does the competition look like, how do their rates vary during the week.When we do our short term rentals we always make it very special.

However, how (to what degree) does the cost of capital fit into the picture or does it? 

The strength of asset protection and confidentiality of LLC's varies wildly from state to state and how well your operating agreement is drafted. 

Florida varies drastically in price depending on location.

@David Garcia- thanks   1) if you plan to lie in one of the units and minimize the down payment - use a FHA loan  as  down payment can be as little as  3.5% of the  price  2) if  not planning to live in one of the units - use a conventional loan and  your down payment will be  consierably  higher  ( the amount  will vary based on the type of property you buy   3)  downside to using a FHA loan - you have to pay  upfront fha mtg ins  premium of 1.75%  ,,,the monthly mtg insurance is  permanent and high ..benefit to  FHA  is low down pmt ,  tend to be better priced  and also more forgiving on credit  4) let me know if yuou would like a FLA based loan person referal and  good luck

However, I recently got accepted into a medical program for my master's degree. 

But this is varies depending on the builders requirements.

I realize that this is both very subjective and varies by circumstance.