some of these have already been done : D
when i first opened this topic i saw a post from richard showing onion skins
if u want layers at least what i know, u can download the arcade-background-scroll extension and make layers like that on backgrounds.
we also just got an august update giving us the piano roll extension. (just look up piano u will find it) We also have this awesome cool thingy for converting.
a random tilemap generator can be tricky because u might have half the tilemap be blocked off.
if u want a bigger screen, just go to javascript, go to the top of ur code and put in this:
namespace userconfig {
export const ARCADE_SCREEN_WIDTH = 320
export const ARCADE_SCREEN_HEIGHT = 240
}