The jumping wouldn't be that easy to do. I mean it could work in maybe 90% of cases but if it wouldn't be detected, it could be frustrating. Especially when you were low on health. If I would make it less likely to treat something as a jump, you could stand on your tip toes and pretend you're flying all the time ;) This could be a bit fun, though. But still, these ideas can be done, but just turned around. Instead of jumping over them, duck below them. I actually want to have small holes in the walls with tentacles (or something like this) trying to grab you. So you have to stick to the other wall or try to shoot the thing.
Jumping from a platform to a platform could bring a bunch of new problems. To keep things calibrated to the play area, when platform moves, I disallow switching platform you're standing on - you can move around freely but for the game, you're anchored to the platform. The problem would be that you jumped, you think you landed, but the other platform already started to move and the game prevented you from landing. You would fall through the floor of platform that started to move. I wanted to avoid falling down but I will reconsider it. Detecting whether someone is leaning over or standing beyond the edge is possible. I would just need to tweak it to make it more likely to consider that the player is leaning. To allow standing on the edge etc.
There is one thing that I like about that key thing. Memorisation. Although because you have to choose from a fine set - numbers to be precise - it can be solved with a brute force approach. But this could be done in a different manner. You have to find some strange, alien like characters, icons, signs, something like that. In the level, just as you described. Then, at some point you have a board with all those characters, and others. If you press the right one, it just lights up. If you press the wrong one, you are damaged. This way you could scale the difficulty of the puzzle. Not only by having a different number of signs, but you may also have a larger board of signs to choose from. (or I could just add alphabet to the numbers, at least for the prototype). So, yeah, I like the idea and I will add that to the list :) Thanks :)