If you're using a still air bator with an auto turner, the reason for raising the floor or putting the eggs in cartons would be so that they stay at the same level and therefore the same temperature inside the bator. Fan assisted bators should be the same temp inside no matter where you stick your thermometer, as all the hot air is being constantly swirled around. But in a still air bator, the bottom of the bator could be quite a few degrees lower than the top. You don't want to go into lockdown with eggs that are sitting at a lower temperature, so you should try to make sure they're at the same lever as they were when they were in the auto turner.
I like carton hatching. It's tidy, it's easy to keep track of which egg is which cause they don't get kicked about when the first chicks hatch, and from my own experience with both cartons and just lying the eggs flat, cartons seem to let the chick zip and hatch more quickly. I cut the cartons down to about half height so that most of the egg is sticking up out of it, and I cut holes in the bottom of each cup for air circulation. Oh, and I use cardboard cartons, just cause that's what I put my eating eggs in...
If you want to keep three chicks separate, maybe best to put a little wire screen down the middle of the bator, cause even if you keep the eggs separate, once the chicks hatch they'll be bombing all over the place and you'll find it hard to keep track of who's who...
