No, you won't lose juices cutting a piece of large meant into smaller pieces. Cut a hunk off to cook and freeze the rest unless you plan to eat it soon. The way meat looses juice is if you don't let it set after you cook
it. Let it set for 5 minutes so the juices settle back into the meat...
I don't think it's good to store things like that in plastic, oil is used in
the process of making plastic. Use tin foil. I never freeze meat, I buy it
fresh.
Frank 2022