We actually just had another bug report about the missing border issue. That's something we hadn't seen before and seems to be a bug with Facebook itself. For more information on what we found from our testing, see our response
Facebook like-box border missing
post.
As for the different size for when Like'd vs not-Like'd, that's not an issue we've heard of before. What actually changes for you? The whole size of the Like-Box, or just one section (header, faces, stream)? Maybe we're just not looking in the right spot.
Thanks,
Alex