First, welcome to the forum, you'll get lots of great help here and you'll quickly be able to maintain your cars by yourself!
As for the tape adhesion, I would recommend spraying it with all purpose cleaner and letting it dwell for a bit, or trying goo gone. Be sure to use both of those appropriately (not letting them dry on the plastic or anywhere where it might over spray/run off on, etc), A steamer would also be a great option, if you have access to one.