Glad to hear you got the plate off. Please post some pics of it, both sides to refresh my memory of what they look like. I have run across these, replaced bearings, and never had to drill out rivets. This must have been an early plate as the later ones did not have rivets. I am pretty sure they can be replaced with a non-rivet plate if needed.
Sounds like you need a drill and some bits for your next B-day! (I got mine at 14 or so and still have it...)
BEFORE you order parts online, call your Kirby shop (if they do repairs) just to see what he has. Have your list of parts, too. You never know what he might have lurking around in the back in dusty bins (speaking from experience!) He might even have 25 1CR parts units in the warehouse like my friend did!
No prob on the questions - this is how you learn. Breaking stuff is also how I learned, so if it happens, we fix it and learn from it as well. So far you seem to be doing well. Take lots of pictures so you know how to reassemble it.
I have almost any motor unit part you need, as long as you are not in a hurry for it; just pay for shipping and I will send them when I recover (probably a month or two out).