Pre-Made Rooms that are generated in random order

So the subject kind of says it all but to give you more of a description. I want to create a challenging platformer where you get a point for each room/stage completed. Each room/stage is always the same size and the end of each one is a pipe that takes you down a floor to the next. How would I be able to design the rooms but have them generated at random/in a random order vertically down below eachother?

This shouldn't be too difficult to achieve. Can levels be played only once, or multiple times? E.g. does the game end when all levels have been played, or is the game endless?

An endless game would be simpler as you would just use a random number generator to pick which scene is loaded next. The first method is more complex. It could be done with a list of all the levels and then just pick a level at random from the list. When a particular level is loaded from the list, make sure to remove its name from the list so that it can't be loaded again.

I thought about doing it that way but I kind of want it to be seamless. Like I want each stage stacked on top of each other so as you move down you can see the previous level you were on and a glimpse of the next one below you

an odd example that will either make sens or confuse you is the way that flappy birds (the only endless game i can think of right now xD) has pipes slide on-screen. The difference being I dont want to spawn one random actor. I want to create a whole room randomly underneath another room creating somewhat of an endless tower. Im assuming I would obviously have to design/pre-build, these rooms. I just dont know how I would go about doing that.

I want each stage stacked on top of each other so as you move down you can see the previous level you were on and a glimpse of the next one below you

To accomplish such scroll effect, use these settings:
<a href="http://static.stencyl.com/games/35118-0.swf" target="_blank" class="new_win">http://static.stencyl.com/games/35118-0.swf</a>

I want each stage stacked on top of each other so as you move down you can see the previous level you were on and a glimpse of the next one below you

To accomplish such scroll effect, use these settings:

SInce when do we have that option? I have been faking it for a long time...

I have always seen that option there.