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Agreed. I've used a bunch of Wordpress SEO plugins, and the latest version of Yoast is the best. Also, some Wordpress frameworks, like Thesis come with enhanced SEO customization options. Title tags for categories is one of them.

It would depend if you were looking to make the new URL your primary site and close the other down completely. If it is an expansion and you plan to forward all of your traffic there and don't care if your other site loses ranking then that's okay. As a rule I recommend using 301's as rarely as possible. Your best bet would be to build up some content for your new site before you roll it out and just link to it from your existing site. Google has changed the game a bit this year and they are really looking at content rather then instant link juice. Building a good link profile and posting some good, unique content on your new page is going to do 10 times the work a 301 would and has a 0 risk level. I hope that helps!!!!!!!!!

If you won't noindex your category pages, my best suggestion is to add unique content to the home page - split out the content so it shows the X most recent article titles & snippets, and separately (to the side of it or above or below it) have unique home page only content - a good couple paragraphs of it should help.

This is also a good linkbuilding resource. http://www.seomoz.org/blog/link-building-101-the-almost-complete-link-guide

huh? A you  asking..... "If people use the backbutton to go back into the SERPs, will that reduce your rankings?"   My bet is YES.  But I have not heard clear statements from Google about that. Anybody know where we can read or watch what Matt Cutts or another inside person has to say about that?