Baby Brine Shrimp Eggs

[Barracuda]

Do they go "off" ie do they have a use-by-date?
If I were to buy 100g for example, I know this will last me a long time, so I'm not sure whether the eggs will still be ok in a year or however long it will take to use up.

Also, how is the hatch rate determined? "Better" eggs? For example:
This one has an 80% hatch rate, and is cheaper:
http://cgi.ebay.com.au/GSL-Brine-Shrimp-Eggs-Live-Fish-Food-Aquarium-20g-80_W0QQitemZ170345524894QQcmdZViewItemQQptZAU_Pet_ Supplies?hash=item27a9626e9e&_trksid=p4634.c0.m14.l1262&_trkparms=%7C293%3A1%7C294%3A30
Compared to this one, which has a 95% hatch rate:
http://cgi.ebay.com.au/Brine-Shrimp-Eggs-Great-Salt-Lake-95-20g_W0QQitemZ160250596302QQcmdZViewItemQQptZAU_Pet _Supplies?hash=item254fae0bce&_trksid=p3286.m20.l1116
Will the hatch rate be a significant thing to consider in making my purchase? Keeping in mind I have never hatched BBS before...

Thanks

[ILLUSN]

store them dry in the freezer they'll keep a very long time, the better the hatch rate the less unhatched eggs pooling down the bottom with your hatched shrimp, unhatched eggs are indigestable.

seperating eggs and shell from shrimp is a pain if you can try and get decapsulated eggs, these have no indigestable shells and even if the eggs dont develop fry will eat the decapsulated egg as is.