I started playing in 2004 and still have both the Official CoH & CoV origional 3' binders that were sold back then and yes they were stackable. Much or the Info is no longer useful due to the added classes, powers, nerfs, adjustments & story line changes, but for looking up old info they still work. I left the game in 2008 due to prison so I can't say what happend to the powers after that.
I only used Consealment power set on 1 character, and found it limiting to what I wanted to do so I never used it on other toons. I like some of the new adjustments made to the game, & I think CoH still is one of the best MMO games ever made, and I would still pay the monthly membership fee, like I was before.