Agreed with everything said, the wire is too drafty, the plate needs to be set with a variety of height, and I would move the water and feed so it is just outside the edge of the plate and they can easily just peak out and get some without leaving the heat. I would also put a towel or washcloth under the plate so it holds the body heat when they are on it, the chicks (and all birds) lose most of their heat thru their feet, so you want something that holds in warmth under them, or they will be passing their heat onto the plastic, metal, wood floor. I have cheap shop towels that I got like 25 for $5 or something, and if they get really crusty I just throw it out, otherwise I just wash them.
Young chicks will wander out of the heat and they are too dumb to remember how to get back, but you can put a light outside the brooder, I use a small table lamp, and put it to the side that the plate is on, and when they are ready to go back they will instinctually follow the light. I use a heat plate sometimes, when I’ve got a lot of chicks and need more brooders, and I mostly use ceramic bulbs that don’t glow, for the first several days I’ll have the table lamp, or depending on placement of the brooder, I might have a hall light on that’s coincidentally well placed. Another issue with lost chicks, one will go out to eat, get lost, and call for his friends. Instead of calling back, the others will wander out to the lost chick and they’ll all pile up out there because they forgot how to get back and there’s no one left to call for directions. They will die from cold, or crush each other if there’s enough of them. Moving the feed and water right next to the plate helps this too, I’ll often put the lip of the container right under the plate, it’s not like a heat light, the plate won’t warm the water and cause them to get into the warm water. I also use small parakeet waterers for new chicks, it’s like a small bottle with a narrow open top tube sticking out, there’s no way for them to get into the water because the trough is so small, and you can put it right next to the plate, and there’s no way for them be able to go around to the other side of a big device and get lost.