Great run down. I think starting basic would be better, only because it would make a more complete "series" for the tutorials.
As far as your platform idea... rather than making the platform change... make the player character change instead. This way, if enemies come into contact with the platform it won't matter. I would use some kind of detector above the player, which if the player is jumping and the detector collides with a platform, the players X.Y coordinates are changed/added to, via a series of events (which over-rides any "solid" platform issues).
~Sol