Moving Pages To Other Domain vs Preserving Ranking

I'm about to embark on a huge mission involving changing just about every URL of all pages on a hand ful of sites. They will all change to a different, yet established, domain. Last time I did something similar (filenames changed but root domain stayed the same), it all went fine. Having been out of the SEO/SE loop for a while, I am looking to speak to a couple of you who have recently completed such a mission.

I have some questions I'm looking to answer as accurately as I can if at all possible. I can make some pretty OK predictions but would be very glad to actually hear from someone who has done this in the past 6 months or so.

1. Will 301s transfer all the 'power' from the old URL and domain to the other domain? With all the 'power' I mean backlinks, PR transfer, authority status, local rank value etc. etc.
2. The current domains and the 'new' one are approxiametly equally as old and have always been owned by the same 'host' so Google probably already knows they are affiliated by host (host as in owner). Will this help preserving rankings?
3. A couple of the sites seem to be of a strong authority status; what are the chances of that being preserved when all of the content is lifted to the target domain? Think of it in terms of About.com snapping up a quality small resource and lifting it to their site.
4. Would there be a benefit in using subdomains for each site in a bid to preserve 'niche' value and authority on a subject? In other words, if you compare it to Amazon, would Amazon stand a bigger chance of ranking for jewellery if they had their jewellery department on jewellery.amazon.com instead just a file name depicting a category like www.amazon.com?cat=jewellery?
5. I'm tempted to build the new site and copy over the content first (leaving the current sites as they are) and then send a small proportion of the traffic via AdWords to the new domain as a test run. I obviously don't want done for duplicate content. Would I risk anything doing that and just blocking the SE's via robots.txt?
6. Doing straight 301's to the new destination might confuse repeat visitors. Does a meta refresh of sorts where I say "we've moved, you'll be redirected" work just like a 301 as far as SE's are concerned? is there anyway of doing a delayed 301 like that?

And many more questions. I have reasonable answers to most of these but I'm looking for your experience, thoughts and ideas on things related to such a task. My own experience is probably outdated.

I would appreciate your input a lot. You can post here, PM as well or if you don't fancy typing, drop me your phone number and I'll ring you, wherever you are in the world. I just need to make sure I'm not overlooking something and cock it all up, loosing 100K uniques a month, potentially.

Really good comments will be awarded one way or another!

 

Had some good feedback, thanks.

What about Google Sitemaps, can anyone confirm this has helped them with a domain change?