I think that with enough make up Bella could look stunning. Kristen is a very average girl so to get her to look stunning she'll need lots of make up. The other वैंपायर wear lots of make up to get them to look that flawless.
I don't think so. Kristen is kinda pretty but she's really not the prettiest girl, I don't really think she'll be that nice as a vampire. We already saw an example of what she looks like- from New Moon. I thought she looked a bit iffy, actually.