Before the season starts, sure... it's a % of the cap. However when rosters are sorted out for the season and people are waived, re-assigned, put on LITR, etc. Those aforementioned players on perma-LITR: Pronger, Savard, Franzen, Nathan Horton... well... they then don't count against the cap.
Yes they do. They never go off the cap, teams are just allowed to go over the cap.