1. The symbols in your questions got messed up, so I'm unsure of what exactly you were trying to ask, but if you were asking about leveling up an Aggron Lv. __ into Aggron Lv. X, yes.
2. I'm going to say no here. Look at Infernape Lv. X for example:
Since EX Pokemon are considered different than their normal versions, I'm going to say it works like normal evolution rules. Since it doesn't say "Put on top of Infernape or Infernape ex" than you can only evolve from their normal versions.
yes, unless for some reason they change the text on a lv x to say place on the regular stage 2 or stage 2 ex, you will only be able to level up a normal stage 2.