I am very very very new to this (did I mention I'm new to this?) but based on a lot of reading through the forums, I would say that they are dying simply because they are hatching so late and are very weak. As JJMR794 pointed out, they should have hatched on the 24th. Its kind of like survival of the fittest at this point... the strong ones will make it, and sometimes the weaker ones do not.
I am very sorry, I know its hard to watch those little guys hatch, or almost hatch, and then lose them. It happened to me a couple of weeks ago for the first time (my first hatch).
Hopefully someone can help you with the seeping issue, but when I had that happen, the eggs had gone bad and I believe the gasses building up had formed small cracks that caused the rotten egg to seep out a little. Do you notice a really bad smell from those eggs?
-Jessa