Plates are able to be turned in with ease. Go to your nearest DMV and hand your plates to a DMV rep. That's all you really need to do. Usually you don't even have to wait in line. That's if you don't want a receipt.
Yes can cancell online and turn it old plates
Yes, you can go online to cancel your registration, as long as your registration is not suspended for insurance lapse(in fact, you need to cancel your registration first before canceling your insurance to avoid an insurance lapse). You can actually keep those plates for up to 18 months after canceling them if you want to use that plate on another vehicle that will be registered in that same person's name.
Not sure but the dmv has decent call services give them a quick call and im sure they can tell you sorry I can't be more help.
Thanks! Your answer is awaiting moderation.