Duplicate content has nothing to do with separate domains. The only thing duplicate content causes in a search engine is that ONE PAGE to be looked at and not included, or ranked lower than the original. You do NOT get penalties from duplicate content unless it is on the SAME DOMAIN I'm so sick of fag marketers lying to noobs.
Now, you can't survive off of dup alone because you will never get into the search. You need some good, unique, ranking content that brings visitors, who then look at your dup content while they are on your site. There is no duplicate content penalty, only frowns on redundancy in the same domain.
Google indexes and ranks on a ONE PAGE by ONE PAGE basis - not your site. So, each post in a wordpress blog may help to build the web of that blog itself, google is only considering each of those pages, one at a time, unrelated to the site it is on, and related only to the topic of the page.
There are many things going on when you are getting into search engines, but they are all irrelevant-looking when you consider page-by-page nature of indexing.
That means backlinks should be on pages related to the page in specific that they link to. And so on.
Autoblog? You need to think outside of the box. You need to avoid google looking at your single pages and saying "I've already got ten of these", or use content that is expected to be on many sites - not text
