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Unfortunately, your photos did not come through. I am unable to assess the damage. It does sound a bit like they have been overwatered, though. Depending on how far gone, and how much bark has peeled, they may not be able to be saved, but I cannot say for certain without seeing it.

A fungicide will be your best defense, but it may not save your shrubs.

Here are some articles that will help:

https://www.gardeningknowhow.com/ornamental/shrubs/holly/care-of-sky-pencil-holly.htm

https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm

Yes, they are hardy in your zone. Here is an article that will help:

https://www.gardeningknowhow.com/ornamental/shrubs/holly/care-of-sky-pencil-holly.htm

If you happened to get the male hollies, they won't produce the insignificant black berries that are about pea sized.

https://www.gardeningknowhow.com/ornamental/shrubs/holly/care-of-sky-pencil-holly.htm

Once you trim them, you can't stop. This will be a constant process, but you will want to do so during winter dormancy, when the growth slows down to avoid the shrub losing its notable shape.

Here is an article that will help:

https://www.gardeningknowhow.com/ornamental/shrubs/holly/care-of-sky-pencil-holly.htm

There are many things that you can do, both, natural and synthetic. Pyrethrins are my go to for most occasions, and you can extract your own from Chrysanthemum cinerariifolium! There are many, many options, though. This collection of articles will help:

https://www.gardeningknowhow.com/plant-problems/pests/pesticides

When you water it, do you remove it from the outer pot? If not, there may be some root rot going on. Make sure to dump out the water in the outer pot after watering. You can trim off those brown shoots. Here is general care:

https://www.gardeningknowhow.com/ornamental/shrubs/holly/care-of-sky-pencil-holly.htm