Hello Kevin,
You will certainly need a hair dryer to remove the old plate, and judging by Derek’s experience -to remove the tape remnants.
You will usually find that the plates are stuck on by 3 strips of pads, and as I said, you can attempt to remove as much of the old pads as possible, but with the potential to damaging paintwork.
I tend to leave the old sticky pads where they are, since they tend to retain some of their adhesion, and I cannot really see much advantage in removing all of that. Again as said, I simply stick the new pads alongside the old and all is well, without extra effort, no damage and no great downside.
Its probably worth getting your new pads from the plate suppliers to ensure they are the correct external useable type.
Worth cleaning the body area where the pad goes with meths - also the corresponding section of the plate.
Kind regards,
Gareth.