You can usually get them off OK by really heating them through with a hairdryer or gently using a paint stripper gun.
As for getting them onto another bat, it tends to not look great. You'll need to find a new adhesive to use. This is not too difficult, there are various sprays, contact adhesives and other types of glues that should work fine. You also need to get the stickers to sit nicely on the bat whilst the glue cures. This is much more difficult, its hard to stop them curling at the edges and also you may find that any chroming or other shiny effects have been spoiled during the removal process.