I know how you feel, as I also did that.
I did a post that maybe can help you.
Emma Alvarez Site: How to recover your Diggs, Alexa and PageRank
With the PR is not clear. You will loose it and regain it after months.
Here's another post about how to use a custom domain with blogger and advantages and disadvantages of having a domain.
Emma Alvarez Site: Why Buy A Domain? Choosing, And Custom Domain With Blogger
Don't worry.
And Happy Thanksgiving Day to all!!!