The newer Palm Desktop software with the Treo should provide a guided migration. My wife moved from a Handspring Prism to a Treo 650. After the last HotSync, the new Palm Desktop software was installed over the existing Palm Desktop. On the first syn...
I don't think it stands for anything. The first Treo phones were released by a company called Handspring, which was then bought by Palm, who kept the name and released more phones.
You can not do it. The Treo 700P and the Treo 700W series all have parts that are proprietary to the OS related to each device. Put the Treo you have now up for sale on eBay and then buy the Palm based version.