Most members believe it makes economic sense if you are a frequent visitor. In the long run it is cheaper than renting like facility (the prime resorts) annually. Note, if you always go to All-Stars, or off-site and are fine with that, then
DVC will actually be more expensive in the long run.
Disney financing is easy. Its interest rate is quite high if you are comparing it to a home equity loan (which, if you own a home, is another way to finance DVC) but somewhat lower than the market interest rate for timeshares.
Resale can be very attractive and cheaper than going through Disney. And all members, resale and from Disney, have same rights and are treated the same. Nevertheless, when you buy resale, you have to do your homework, particularly if you need finanicng. You have to calculate total cost to make sure deal is better than Disney because a higher finance rate can mean that seemingly bargain sale price results in total payments higher than going through Disney. Also, resale is the only way to get sold out resorts (BWV, OKW, VWL).
You cannot get a Florida AP as a DVC member. That is actually spelled out in the official documents.
If you rent, you make the reservation for the guest you are renting to. It is just like being a landlord -- if the guest fails to pay, it is your problem, if the guest destroys the unit, Disney can have you pay for the fix. Unless you rent to the extent that you can be deemed to be in the business of renting units, you do not have to collect or pay the Florida sale tax.