having roosts of different heights is not really recommended. they will end up all jockeying and competing for position on the highest one(s) every night because these are always prefered. having them all the same height easily eliminates that problem and the stress it creates.
just for another perspective, im not a huge fan of the dropping board/droppings hammock method-- to me thats just more work. with an active, good litter whats falls under the roosts gets incorporated just like in the rest of the coop, or if it doesnt always you can use a tool to incorporate it...
ive known people to have separate buckets of scraps, edpecially one that goes to chickens and one that goes to compost. but for us its always just ended up being easier to send it all to the chickens and let them do the sorting by eating what they will eat and pooing all over the rest. Well, not...
Haha, I should have clarified by writing "a properly managed indoor worm bin." :) Situated ideally in a laundry room, closet, etc. or wherever there's space out of the way. Personally I would be more inclined to have one outside, but I know that plenty of people with no other option keep them in...
Reading this, I had another thought to add: have you considered a worm bin? An indoor worm bin is pretty inocuous and could take care of your excess scraps, while excess worms could be fed to the chickens...