1 - Use the TiledBackground for more easy and precise positionning !
2 - I don't think ... but I'm sure that it's on Scirra Team to-do list ;)
3 - Please go back and read the second answer ! ( Too lazy to re-write it :3 )
4 - Layers - Just tweak their opacity to make the level change and the magic operate :D
That's all folks !
Cheers !