I've read in the reviews that some of the episodes are edited on the DVDs. I searched, but I couldn't find a list of the cuts.
So I would like to know which seasons contain edited episodes, which episodes those are, and, if possible, I would like to know the exact scenes which are cut as well.
Thank you in advance!

There is a major cut from "I was A Teenage Taylor" in "The Complete (actually not-so-complete) Sixth Season" DVD set. In the opening sequence Tim and Al share their Halloween pranks on each other and then after the title sequence we go to the Taylor home. What's missing is a scene where Tim introduces Al to his Halloween guy Larry backstage at the Tool Time set. It really makes it strange when Larry appears later in the episode as a key person in the plot of the story. I tried contacting Disney/Buena Vista right after the season set was released, but got nowhere with them. They essential blew me off in an email. Hope that helps in whatever way it can.

Season 6 is when the DVD quality certainly went downhill. I had no problems with the video content in the first 5 season sets and the packaging was great. Beginning with season 6 the video content became poor (signs of video compression issues) and reports of missing scenes (DVD cuts) became common.