How uninstall an App

Regarding the copy, just be sure to keep the directory structure (e.g. X:\PortableApps => Y:\PortableApps).

I would recommend checking out the excellent instructions on how to uninstall an app at https://portableapps.com/support/portable_apps_suite#removingapps, that is probably a better explanation than I could come up with.
As far as copying to another thumbdrive the easiest way is to open both in a windows explorer window, and just select everything on the drive, then just copy everything over to the new one. I tried to copy my old drive to a folder on my desktop and had some folders in my OpenOffice.org Portable installation that I could not copy over due to the file path being too long. I had to go in and edit the file path on a few folders to make them shorter before I could do anything with them because windows had them locked. After that experience I have come to the conclusion that it is best to directly copy from one drive to another, it will work just fine.

Hope this helps

Artos