They can be frozen if necessary, but double-bag them, squeezing out as much air as possible before freezing. The same goes for eggs that can not be cured immediately. If frozen, pre-wrap them and double bag them to prevent freezer burn or refrigerator odors from penetrating the package. There is nothing better than frecgiy cured steelhead eggs. On a given day, one bait may work better than another, but fishing with properly cured eggs has it's own special rewards, especially if you've cured them yourself.
Most anglers prefer an egg loop tied to the hook.
Nothing stops your heart faster than seeing your buddy reach into your egg sack, pick up one of your beautiful baits, and just thread it on the end of the hook with nothing else holding them. Eggs are dainty, and they must be fished that way. I have been using a double hook set-up for the past couple seasons. The top hook holds the bait while the bottom hook, tied immediately underneath, follows as an invisible stinger. This is for those short-hitting fish that sometimes just nose, or rattle the bait without actually biting it.