Whatever works. Heck I hatched my first 3 eggs under my lamp on my nightstand, in a shoebox, filled with cotton when I was 12. Two hatched. LOL
I remember people putting eggs in a bucket on a sunny porch, covered with a towel and chicks hatched!
Do you even have a thermostat? I don't see one.You can get one for a hot water heater for less than $10 at HD or Lowe's. You need to wire the thermostat into the light fixture. I've never heard of someone ajusting the height of the light in an incubator. LOL I guess anything could work.
Here's...
I don't think so, but when you get a chance, use a drill and leave some small holes. The chicks need oxygen while they hatch. Did you check out the hot to pages with the homemade bators?
Make sure the light is as close to the thermostate as possible with about 1/8 to 1/4 inch of space behind the thermostate, so it can read the temps correctly.