What's your question? Ask

This happens normally when the plant is not getting enough water. Try increasing the water to the plant. It may also be a fungus or the roots are damaged. As a precaution, treat the plant with a fungicide and check the roots for damage.

You may need to increase watering, at least for the first season. Newly planted plants need large amounts of water to establish themselves well. Their roots were either restricted or cut to be able to be in the pot, so are not large enough to support themselves well yet. Watering more will help those roots grow. With shrubs, it takes about 3-4 months minimum of good watering to get them well established.

Increase watering and make sure that you are watering deeply, so the water gets to all the roots.

Late winter would be the right time for blueberry pruning in your area.

Severe pruning will not kill the plant and normally results in bigger but fewer berries. The best time to prune is when the plants are dormant, which is late fall through very early spring. This article will help: https://www.gardeningknowhow.com/edible/fruits/blueberries/blueberry-plant-pruning.htm

It depends on the variety as to whether they lose their leaves or not. But even the ones that do lose their leaves should not brown on the edges, so it is likely caused by a lack of water.

I would wait until spring to do this, but I will warn you that digging out a 4 year old plant will cause it great stress. You are most certainly guaranteed not to get fruit from it the year you dig it out and, if it does not die from the stress, you may not get fruit from it the following year either. Choose carefully before you do this.

If you decide to go ahead and place it in a pot, yes, pruning it back will be helpful in reducing stress. This article will also help with preventing transplant shock:
https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm