Hi
you can start feeding now - dont overfeed though as the worms will eat all the coir block as well so they have loads to eat.
the white things are mites, and they actually like damp conditions, so adding water probably made them florish.
Dont worry - they won't cause any harm to you or your wormery
it seems that your worms are taking longer than usual to settle in, but it will happen.
Worms live in the top few inches of soil, so dont worry - thay are where they should be.
and eventually they will be in the food and visable when you open the wormery.
Make sure the food is covered at all times, this prevents any fruit flies from entering
Best of luck
Ronnie