It could only be the yeast which was not effective. YOu should sprinkle some over water and leave for sometime. If it does not start to froth in 10-15 minutes, buy a fresh packet.
In any case it takes a few attempts to get it right, because each oven is different too. Temperature of the oven is important too.
Flat and cracked could also mean it rose and fell.

You can use it in an emergency but not ideally.
A Dutch oven is a heavy bottomed deep pan with a fitting lid.

You have understood the recipe right. You are most welcome to ask what ever you want, do not feel conscious of it.

It is only by making loaves that you can cut slices! You can use the whole dough if you have a big enough tin for it (loaf tin).
Temperatures are given in the recipe.

I think I wrote to you earlier that 1 egg=1/4 cup milk+1 tsp vinegar.

Sorry I do not have rusk recipes.