So long as you have a warranty, you are entitled to service & repair from someone. Find out who that is going to be, the dealer should be able to tell you. Also make sure you are getting the original warranty if this is an older floor model.
With referance to the warranty, you have to read the fine print, some warranties will let you move it and some will not. Most are not transferable if you sell it with the house, although I believe Marquis is an exception on that one.
Do not buy a spa (or anything for that matter) sight unseen, which is what you will get if you buy a Thermospa. There are lots of good spas out there, Hotspring, Dimension 1, marquis, Coleman, Sundance to name just a few. Always make sure you are buying from a dealer with a good reputation.
Go to some of the major spa players web sites, enter your zip code in the dealer locater section to find out who sells what in your area, then narrow your search down to 2-3 spas and wet test, concentrate on comfort and size first. Some brands to consider...Marquis, Hotspring & Tiger River, Dimension 1, Caldera, Coleman, Sundance, Arctic. Good luck.
The Escalade is a good steel pool, you did not say what Esther Williams model you were interested in, they have many differant types, was it an alluminum or steelpool. If you have the room and it's in your budget, you may want to consider the next size up from the 18', it shouldn't be that much more in price and it gives you a lot more room, as your son grows and gets more play pals an 18 may seem a bit confining.