I find that I can freeze the embryos in a cryomold filled with OCT on dry
ice  (helps with orientation too) and I get no cracks (as compared to
liquid nitrogen/isopentane) and get quite decent morphology and
preservation.

I usually store my antibodies as the manufacturer indicates.  Sometimes to
avoid freeze/thaw I might add 50% glycerol and store at -20C so I can take
what I need without thawing the sample. Other antibodies I leave at 4 deg
and they work like a charm for years. I usually don't put my Abs at -70 deg
but I go through them quickly so don't need to store that long really.
Like someone mentioned previously, controls are essential.

Andrea