I should have waited longer.

I have a question. I am new to hatching and am trying to figure out what I am doing wrong. First, you must know that I used a 3 egg incubator (Just got a bigger one for mother's day) and I put three eggs in it. I threw one away because I could tell it had stopped growing. This is the second time I used it. The first time only one hatched and it hatched on day 23. The other two died. So this was my second time in hatching with this little incubator. Anyway today was day 24 so I decided to open them up (I hate doing that) but I really want to learn how to incubate. Anyway, when I pipped a whole in it I heard little peeps so I did the other egg too. It shocked me because i thought they would be dead. Then I got nervous that they were just having a hard time getting out of the shell because it was three days late. So I opened the shell up a little more. Of course they died after a few seconds. I opened it up completely and the yolk was still big. My question is why aren't they developing and not hatching? Should I have just waited a few more days? They seem developed. Also, how soon before they hatch do they take in the yolk? My thermometer says 100 degress all the time with a little variation that I adjust for. The humidity seems right because the were fairly wet. The other question I have is would it have been better if I just left the little hole in and then left it alone? Do I just go through the shell? I hate to just throw them away if they are still alive and I hate to open them up only to see them die. I would appreciate any suggestions. But no judging please, I feel bad enough. I know some people have said to just throw them away so your flock doesn't become weak or inherit longer hatch times and some people help their chicks. But I am not hatching successfully yet and I want to learn to do everything I can to make them healthy and strong. I can work my way up to throwing them away but I have to feel confident that I am doing everything right first. Any objective suggestions would be appreciated.