On flax seed:
The reason, as I understand it, that flax seed oil or store bought meal is not recommended is because it goes rancid so quickly.
The flax seed itself will keep for a long time just as wheat berries do.
Most people get a little electric coffee grinder ($10) and grind up a small amount of flax seeds just before using. When ground they can be hidden in almost any food. Don't taste bad all alone either.
If you Google "flax seed" you will find several companies that include a grinder with your first order.
I was surprised to find out how quickly the ground seeds went rancid - A matter of less than one hour for fresh ground seeds.