How does the gained PR change with the amount of backlinks from various pages on the same domain name? For example... Footer link exchange with some forum that has 100k indexed pages. I know i will get more visibility = therefore more traffic, but what happens in terms of PR?
WHO CARES! Actually it depends on the PR of the site linking to you. You really shouldn't expect too much though.
From my own experience you only get a slight improvement. Good point, PR is a bit overrated... (just a bit)