If you shine the light through the air sac you should be able to see veins along the edge even in a dark shelled egg completely full of chick.
A heat lamp bulb is way too hot for any use indoors. You can melt a thermometer with that. A 100w bulb is borderline depending on the temp of your...
Very very bad to shake a developing egg particularly in the first week. Good way to kill them. Other than that odds are you could still hatch some. I had a broody get killed by a coon in the middle of the night and my husband found the mostly broken eggs in the morning. He figured they were...