Marco and company are a legit brokerage for sure.on the build side  this depends on how much money your sending and if your sending to escrow or direct to the builder. also I am building in Ocala currently and time lines are no where near what we expected . and its almost impossible to control cost up front.so as long as your OK with flexible time lines  ( and believe me no builder wants to go long) and price of material fluctuation then you wont be frustrated .

It depends on the state.

But it’s important to understand the legal guidelines, which can vary a lot depending on your state.In many states, if you’re advertising a property you don’t legally own, you may need a real estate license.

Places like Taos or even parts of Arizona can have year-round appeal depending on the setup.

It shouldn't be too expensive in Jacksonville though depending on the condition. 

But also, I would say that single family you will likely have longer term tenants depending on your area and how nice of a place it is.But a duplex you have to deal with managing two units for the same rent as the single family.  

One is dependent on many X factors like economy, inventory, mortgage rates, the other two are in the hands of the investor. 

It would depend on all of the other fees that are included.

I guess it just depends on what posts you chose to read. 

Short term rental operation is not passive so what strategy you decide to use depend on how active you would like to get involved.