Is well-septic a disadvantage for a property in Florida making it less desirable to rent/re-sell?

This lack of control can be a disadvantage if you disagree with certain decisions made by the condo board.

@Arthur Kineard You are at a disadvantage from the start , you are not in the "click" . 

If you go over 30 days, you will enter into the 'tenant' territory where they have rights, and depending on the state may put you at a disadvantage if you need to evict - check into that.Another option: sell that house and buy one where you are allowed to do STRs.....

There are advantages and disadvantages to both options.

What are advantages/disadvantages of partners funding the purchase price of $350K with cash, and financing the rehab $150K?

If you are listing STR it would not be honest to call it a second home on a loan application and no advantage anyways only disadvantage of tougher to qualify with no rents.

Advantages/Disadvantages? 

The advantage (which is also the disadvantage) is greater leverage on the mortgage as an owner occupied property.

For tax purposes LLCs can be taxed in 3 ways based on circumstance:-Partnership (default for multi-member LLCs)-S-corporation (works for both multi-member and single member LLCc [needs an election])-Sole proprietor (reported on personal 1040)S-corporations are extremely tax disadvantageous when it comes to buy-hold real estate.