Hmm....you ask a lot of good questions! LOL
First of all, if you're interested in real estate, I can put you in touch with an excellent local realtor who specializes in homes in STR (short term rental) communities near Disney.
In the US, it's very rare for someone to pay the listed or advertised sale price of a piece of property, usually you negotiate the price downwards (especially in today's soft real estate market).
There are all kinds of other costs, such as mortgage closing costs, title insurance, closing fees, etc, that they add on to the sale price at a transaction closing, again, a realtor or mortgage person would be best to advise you on this.
Would I buy a new home or resale? Well, depends on you! You get a warranty from the builder with a new home typically, which is nice. With a used home, it may already be furnished and up and running. In a new home you're going to have extra expenses to furnish it. In a used rental home, you can buy it basically ready to go, and include the furnishings in your mortgage. In Indian Creek I don't think there are any new homes for sale though. (JMO, but this is probably not where I'd buy in the area right now, again, ask a realtor for advice on this though!).
Mortgage rates depend on many many factors, such as your down payment, type of the loan you get, term of the loan, and your credit rating. You need a mortgage broker to help you here...a good realtor should be able to connect you to a good mortgage lender.
Monthly mgmt, maintenance, cleaning, taxes, pool heat, utilities, HOA fees, insurance, etc, all vary depending on the type of home you buy, and the resort it's in. I could tell you what it costs to run a townhome in Windsor Hills for instance, a larger pool home would most likely incur higher electric bills, for instance. In our resort we pay HOA fees, but our cable TV is included in the price. So is our exterior landscaping, exterior building maintenance. As part of our monthly MC fee they include weekly pool maintenance and monthly pest control, some MCs do it this way, some charge for everything separately.
Our homes are pretty well occupied...I'd say 40-45 weeks per year, but we're on the high end of the occupancy scale, most people don't get that high of an occupancy rate, just so you know. It has a lot to do (I think) with being in the right resort, having a very nice place, and good marketing, MC, pictures, etc., at least it seems to be working for us!
Would I do it again? Absolutely! It's been a lot of fun! I get to talk Disney with people every day basically!

The one thing I would tell anyone looking to do this, is you get out of it what you put into it, and if you want bookings, you will need to work hard at it! I would not count on an MC getting you any bookings, I would count on doing it yourself!
I am thinking about buying another townhome once I find a new job, so if that gives you any indication of if I would do it again, the answer is yes, definitely. I personally think the market being very soft right now makes it a great time to buy, if you can afford to. You're in this for the long haul....if you hope to make money over the short term, you will not, most home owners lose $$ on their STR homes, the place you might make a profit is in the long term appreciation of the real estate.