Pieris plant

The ground is best but I would say terracotta depending on local weather conditions.

makes no difference really, its personal preference. either way check that it is kept properly watered. Welcome to GoY too :o)

Only difference part from appearance is that in terracotta it will need watering more often because water evaporates through the sides of the pot as well as the surface.

I have one in the ground & one in a plastic plant pot & they both do well, if putting in to a Terracotta pot I would put a plastic pot on inside it or line it with plastic and add some water retaining crystals and water as needed :o))