I don't have any info on redirects but I will tell you my experience with Google. I first changed some names by addidng hyphens to separate words in the title of the page: example usefullinks became useful-links. I totally lost all
PR on that page. Secondly, I created a subdirectory and moved lots of pages to it. example: a bunch of product pages with shopping cart info. I lost all
PR on those pages.
The good news is that within 60 days all the
PR returned. I think it took Googlebot that long to re-index the site.
I have no info on other search engines as Google is the only one I use for optimization.
Good luck with your problem.