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Assuming this is a Boston fern, this article will help (would apply to most other ferns as well): https://www.gardeningknowhow.com/houseplants/boston-fern/trimming-boston-ferns.htm

Do you have a picture of the offending plant? This could help us determine exactly what it is and how best to eradicate it.

Fern pests usually include caterpillars, mealybugs, false spider mites, scales and thrips. While I cannot say for certain which insect is causing the problem, you can treat the plant with neem oil to take care of most all of them. As for the biting, I can only suggest that you place some insect repellent candles or something similar in the area to keep the bugs from bothering you.

No, they may stop growing for awhile after planting, but they wouldn't fall over and break by themselves. It sounds like something was stomping around in them --- dogs? cats? deer? woodchucks?
If the stems are broken through, cut them off. If they're just bent, you can tie them up to a stake. Keep them watered, they should send up new leaves after they get their roots going.
Here's an article on growing these guys: https://www.gardeningknowhow.com/ornamental/foliage/ostrich-fern/growing-ostrich-ferns.htm

They don't really need fertilizer, because of the leaves and debris dropped by the oaks. Also many ferns can be damaged by too much fertilizer. If you feel you must, once a year in late spring sprinkle slow release balanced (equal numbers, or 3-1-2 ratio) fertilizer.

Select a pot a bit larger than the spread of the fronds, and use soil from the forest in the bottom and to fill in around the roots; you might add some sand or perlite to it first. This article has more information: https://www.gardeningknowhow.com/ornamental/foliage/ferns/transplanting-ferns.htm