questions regarding duplicate content

[Stever]

So these landing pages, even if they were original contnet on each, would not have any other incoming links. all incoming go to index page. but the site map points to them so the spiders know they exist. So if they are well optimized for a specific keyword phrase, (filename, title, h1 tags, good sprinkling of keywords in content) should they still get ranked well in SE where the only PR for the actual pages comes from the PR for the main page of the site? Or do i have to get some backlinks heading to these pages?

Been looking at some pages that come up at the top of google for some of the phrases i'm targeting. Some of these have 0 PR but the main page for the site has good PR.

Are these landing pages a good idea or a waste of time? providing i make them more original.