Question on Bookmarking..

As I understand it, you can use bookmarking to get some backlink juice for your articles or site. Bookmarking is relatively new to me, so perhaps I misunderstand the purpose behind it.

Being relatively new to IM I've been researching things the past few months, taking and comparing notes and then trying what seems to be the right things to do looking for a small sliver of evidence that what I'm doing are the correct things.

Before I start publishing to a few more article directories, I thought I would go back and fix what I already had out there. I went to a 'goarticle' page I have and updated the content to be unique vs being the same article I submitted to 2 other directories.

I used pingomatic on the article, then to DIGG to bookmark the article again since the original submission (30+ days ago). DIGG came back saying the article URL had been widely reported by users for the following reasons: ...

I'm still learning the ropes, so that doesn't phase me, but is this common now days for bookmarking articles?

If we're spinning or writing unique articles and publishing to several directories, the goal is to gain as many backlinks as possible to help with getting your site to page 1.

My questions:
1. Should we only bookmark the article URL on our web site?
2. Is this method obsolete with bookmarking sites cracking down on this technique?
3. Is bookmarking for long term backlinks or short term traffic bursts?
4. Is bookmarking for simply getting your site indexed? Should a site be indexed before you bookmark it?
5. Would submitting the URL to a burst site like wwwDOTsocialposterDOTcom hurt your site (deindexing?) or it's position if you blast it out to every site on the list?

My ezine article is on page 1, spot 3, so the keywords are not competitive. The free blog site is falling in the SERPs, was #495 at one point and last I checked today it's now at #661 and falling. I'm just trying to learn the right techniques to raise it so I focus on the right systems.