That should be fine. As long as the content you're linking to is highly relevant to the web2.0 post, there's nothing to worry about.

Yes a great way to get backlinks from your own sites..

Your scenario of only 3 posts pointing to 1 page is fine, but I would also start linking to other pages. I always aim for everything to look as "natural" as possible. You start leaving a footprint if you're only linking to one particular page.

You don't have to link to other sites but think to yourself (what would someone who didnt know about SEO do). Then do whatever you think a laymen would do.

In my opinion nobody ever links to just 1 website. They link to lots of them. Balance it out.

If you are linking more than once to your site in each post then that's a big footprint. Try to make it look as natural as possible.