Not in my experience - if they have been properly packaged and stored.
Normally, frozen vegetables are not thawed first but are cooked from frozen.
Thaw = to no longer be frozen Thawed state is the state an object is in when it no longer is frozen. (it might still be cold but should not have any frozen parts, even on the inside)
Any liquid or solid shrinks when frozen; the molecules contract. Molecules expand when thawed.
Food which has been cooked can be frozen, even if it was frozen prior to cooking. BUT Frozen food which has been thawed, but not cooked, should never be re-frozen. Nor should food which was cooked, frozen and thawed.
When it is not longer frozen!
yes
Fish will weigh less after it is thawed because it loses some water when it is thawed.
If the meat was frozen but now it isn't, I would call it thawed.
yes
No. They are dead and do not reanimate.
Yes
It is not recommended to eat any foods that have been frozen, thawed and refrozen. You can, however, thaw food, cook it, and then freeze it.