Sorry don't have any info on the taxi prices.
If you mean the Disney Resort buses which take you from the park back to your hotel, they will run for a while after park closing until the queue is gone. Christmas Day and the surrounding period they will run very late, I think the Magic Kingdom is open until midnight, not sure about the other parks. Park times should be up on the official disney worlds site
www.disneyworld.com some time in October hopefully.
HTH
