Answer: Tomatoes do grow amazingly big and heavy!
In my experience the purchased cages are not usually strong enough. Instead, I tie the vines to sturdy stakes about 5 feet tall or make my own cages out of extremely sturdy wire mesh (not chicken wire). Another alternative is to simply let them sprawl on the ground, although this makes harvest a bit difficult. Any of these methods is simply a matter of personal preference -- they all work.
If the tomatoes on the broken vine are colored and nearly ripe, then bring them inside if you wish. They will ripen at room temperature on the kitchen counter (keep them out of direct sun) but they won't taste as good as the ones that ripen on the vine. If only part of the vine is damaged, remove the damaged section and leave the rest to continue growing.
As far as repelling birds, short of keeping a cat, you might wish to try any one of a variety of "scarecrow" options ranging from home made to purchased. Good luck with your tomatoes!
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