MT Import: Excerpt to Custom Key?

I’m just migrating to WordPress, and I’m mightily impressed so far. I have some questions about fine-tuning the import process though:

– On one MT blog, I abused the “excerpt” field for ratings. I can import this blog and the excerpts stay in place–so far so good. But instead of perpetuating this peculiar use of the excerpt field, it looks like I’d be better off using a custom field with key=Ratings for this. Is there any way I can batch-move the excerpt field to a new custom value?

– The old blog used to be private, and I’d like to individually approve posts to go public on WordPress. Is there any way I can default all imported posts to “private” and assign a password?

Thank you kindly for your help.