Hi Mark!!!
Yes, I think you can sand the big plate a little more (those buttons look great!!!).
Reference images
Regarding the other one, I think that trimming the bottom part a little will solve the problem.
Reference images
You’re doing a really good job!!!
Hello Mark, welcome to FISD.
While you are waiting for your kit, you can do some research on the forum (check out some of the previous ANH build threads...).
Of course you can do this, Chris!!!
As Joseph says, don't try to rush. When in doubt, always ask before cutting or gluing (don't be afraid to ask lots of questions), and be sure to add photos(a picture is worth a thousand words) ...