Some evergreens will survive & be just fine in containers unprotected, depending on their ability to withstand zonal temperature swings and their resistance to dessication. Others are better if moved to a protected area, like the north side of a heated building out of wind & mulched of buried near the foundation. There are lots of strategies that will allow you to over-winter evergreens in containers. I have at least 150 evergreens in small - large containers that are in various stages of development and destined to become bonsai.
Your choice of pot size depends on the size of the plant material and your choice of soil. If you use peat/compost/coir based soils, pot size can be a critical consideration; but as the particle size of the soil increases until the particles are large enough (around 1/8"), as in the 5:1:1 mix and particularly the gritty mix I use, there is no upper limit to the size of the container appropriate for the size of plant material, no matter how small the plant material is.
Turface is calcined (high-fired) clay granules that are fused together so they're like an extremely porous ceramic. They are large enough that they guarantee superb drainage & aeration, yet porous enough that they hold lots of water in their internal structure.
... easier for you to decide what's closest. There would probably be dealers in Scranton, if that's easier.