Things sound good so far. You remove the turner, it will reduce risk of chick injuring itself, and save you some scrubbing. If all the air cells are good you can either lay to hatch or hatch upright in trimmed down egg carton. If some of the air cells are saddled or loose hatch those upright. Good luck!
I'd leave them alone. If you have a cardboard box around, you can make them a 'huddle' box. Basically, you just cut out an opening so they can get in and out, and it helps them feel more secure, plus retain a bit more body heat while they feather in. Removing them from the flock would just mean reintegration stress later on. At 4 weeks they do generate quite a lot of body heat, and huddling together they way they are is likely keeping them all plenty warm. Chicks are much more hardy than many think.