detecting dupe content - new content to existing site or new domain?

[newreality]

Background:

Two days ago I added 12 new pages to a site (Sat).

This is on a PR2 site having about 3 relevent pages linked to it.
It is a contractor & general remodeling site.

anysite.com/projects/(pages here)

The site has only 3-4 pages relevent to the new content topic and is 6+ years old.
.................................................. ........

For reasons of better indexing, I have found a domain name much more on topic -- it contains the most key work domain name 1st. And the target phrases contain 'roofing' lst in sequence.

ex: roofinghelp.com

All the articles of new content are about roofing.

Of note is that many of these are 'how to' articles and that there would probably be 25-30 pages in all if moved to a new name.

Questions:

a) If I am to pull the content from the existing site, how long approximately might I have? Major concern is the risk having duplicate content show. But don't crawlers have to go over new pages twice? The second time around to confirm? I've just seen Google caches for July 12th, Sunday.

b) Would the move to a new domain be suggested starting fresh? Are we still taking 6 mo.'s plus for new sites? (not to mention getting basic backlinks, etc)

c) If I wait, and try and see how things go at the existing site, and later decide to move to new domain -- how much time should lapse between moves OR should everything undergo a heavy edit just in case?

[JohnW]

if you are moving the content to a new location just do it, and 301 each old page to the new page all at the same time. Whatever value/trust/whatever the old pages have should follow the 301 to the new pages. at some point you should ask the people that link to the old site to change the links over to the new site but I would wait 30-60 days before doing that.