You keep hearing different things from CPAs because international tax as it relates to the US is complex. 

It’s like a sales tax. A

Unfortunately most tax savings strategies require spending $1 to save a certain amount of tax. A

It's not the tax as I just have to give the information to my accountant (although it got certainly complicated, when I tried to do it myself - mistake.)

For me I bought a home in Summerlin and moved my residency to a state with no income tax.. as I generate income in 14 states a few of which have no state income tax.. so that helps. 

They pay very little property tax as the home was purchased a long time ago and isn't subject to the normal rates.The question is, is there a way for them to keep their current house, pay off / refinance the existing mortgage or get another heloc in a way that would eliminate the need for the windstorm insurance, rent the house out, and get cash out to buy (mortgage) another property?

In Florida, the buyer may have to pay state and county mortgage tax as part of closing costs, but the seller pays primary tax for the purchase.   

Basically this just adds additional cost in the form of transfer tax. As

Does your state have cap gains tax as well?

They must pay income tax as they earn or receive income during the year.Estimated taxes – If the amount of income tax withheld from a taxpayer’s salary or pension is not enough, or if the taxpayer receives income such as interest, dividends, alimony, self-employment income, capital gains, prizes and awards, they may have to make estimated tax payments.Self-employment tax – This is a Social Security and Medicare tax.