If the eggs are going to blow up you'll smell them beforehand. If they aren't stinking they aren't going to blow up. To keep your unhatched eggs in the right position you should use an egg carton. Then the little ones can run all over them and not disturb them. The 3 eggs that you can see chicks in are probably right before the point of pipping, they usually 'fill' the air cell at this point.
For future reference, the eggs don't have to be turned the last 7 days or so. They chick/duck is big enough at this point to keep itself unstuck. So if you have early pippers again, just turn the turner off and leave them in the turner.
Also, since I assume you set all these eggs at the same time, yet have such a variable on the hatch dates, I would suggest that you check the temp in your incubator. It sounds like you have some hot/cold spots in there. Does the incubator have a fan?
thanks so much for your responses, we weren't sure if we were conected or not. true story, the early bird is doing fine and has been joined by 2 more of his buds (day 25) a fourth is pipping as we write. our new "first hatch panic" questions are ...when we stopped turning what do we do to keep the hatched ducks from knocking over the unhatched eggs we positioned all w/ the air sack up when we shut down the turner. 2nd question... we have 3 eggs in the incubator that you can almost see the chicks thru, this doesn't look right and it's almost like they grew to large, i'm not seeing the air sack. should we discard them now or wait and see. i've heard of eggs blowing up and don't need that.