Sure... but it will more then likely be over cooked. Shrimp does not take long to cook. Your shrimps texture may be a little tough. But YES, you can fry pre-cooked shrimp.
Shrimp cocktail is not cooked, though the shrimps will be par boiled and cleaned before you add your sauce
no
The recommended amount of shrimp per person is 1 pound of raw shrimp or 1.2 pound of cooked. For 60 people you would need 60 pounds of raw or 30 pounds of cooked shrimp.
It's not a good idea. Shrimp don't have much of a shelf life anyway and they will probably turn mushy.
yes
Shrimp Melanosis
If shrimp is not cooked, it will be a grey color. If uncooked, cook until shrimp turns pink, plus one minute. If shrimp is pre-cooked, cook until it has been heated through.
Fried
Yes.
Until its cooked....
Without looking at the package, it may be hard. Shrimp can be all sorts of colors, too. It's usually pink. When you cook it even for a short time it turns white. When shrimp is cooked, it turns orange-pink in color. If it is in a package, there should be something printed on the package to indicate that the shrimp is cooked. I knew it turned either way, but that's right!