Hi experts

i am kind of new person here
since google introduced its new algo for ranking
the rules of the game seem to have changed

my question is
how the article linkes work
and to be more specific:
1. how different articles must be for google to treat them as different pages, so that links would count
2. when submitting articles to article "farms" for how long the article is kept there. especially when it's a paid service to place articles on 20000 sites or so. you know there are some spam mails that you get sometimes from nowhere.

will appreciate any comments on the topic