#1. A lot of the original Trackmaster and some Plarail/Tomy trains use what we call 'Flat Drives' and yes, they can be noisy. Other trains that don't use the flat drives are quieter. The one thing that Trackmaster did right with the new version is that they are quiet and this must be due, in my opinion, to fewer gears from motor to wheel.
#2. Others here know much more than I do about this subject.
#3. All these trains can run on any tracks whether they be Plarail, Tomy, Trackmaster, Wooden or Trackmaster II as they are about the same gauge. The question would be how well they run. In my opinion, not based on my own trials but from watching and hearing about others, is that even though the original Trackmaster and Tomy/Playail can ride the rails of Trackmaster II the traction is not very good and they can't maneuver the gimmick hills of the Trackmaster II tracks. The Trackmaster II tracks have the open slots that fit the cogged wheels of their engines they have making the original Tomy/Trackmaster/Plarail engine wheels slip. The same can be said in the opposite as the cogged wheels of the Trackmaster II engines slip and lose traction on the original Plarail/Tomy/Trackmaster tracks.
#2. Others here know much more than I do about this subject.
#3. All these trains can run on any tracks whether they be Plarail, Tomy, Trackmaster, Wooden or Trackmaster II as they are about the same gauge. The question would be how well they run. In my opinion, not based on my own trials but from watching and hearing about others, is that even though the original Trackmaster and Tomy/Playail can ride the rails of Trackmaster II the traction is not very good and they can't maneuver the gimmick hills of the Trackmaster II tracks. The Trackmaster II tracks have the open slots that fit the cogged wheels of their engines they have making the original Tomy/Trackmaster/Plarail engine wheels slip. The same can be said in the opposite as the cogged wheels of the Trackmaster II engines slip and lose traction on the original Plarail/Tomy/Trackmaster tracks.