Question #1: Thuja occidentalis 'Hetz Wintergreen' aka 'Wintergreen' Evergreen Nursery online sells them, the true cultivar, and a great price. Do not buy them from Musser Forest, Musser sells seedlings of Hetz Wintergreen and it's in the fine print. #2 Rhododendron maximum or Viburnum x pragense Dax This post was edited by gardener365 on Wed, Apr 9, 14 at 15:33

The FAQ has some suggestions... Keep in mind fast growers are not always the best choice if they are messy and/or have invasive root systems. Check with a good nursery about leaf, fruit, and flower drop as well as what the root systems will do to the surrounding areas. Here is a link that might be useful: screening suggestions from FAQ

A lot of the clumping bamboos (most, I believe), that are hardy in zones 7 and 8 are subtropical mountain species. Which means..., they are not as hardy to extreme cold or too extreme heat as that notorious running genus, Phyllostachys (you don't wanna go there!). F. rufa seems the most commonly available in the Mid Atlantic area. It is a nice species and does put up well with our hot nights (a potential issue with many of the mountain species). It has seen temps from 4F to 109 without any burning. It is not cheap, and you will not get a privacy wall overnight, but will, eventually, if it likes its positioning. Some shade from the hottest sun is definitely a big advantage. It is well-behaved and will not be invasive, but will form a dense grove. We have Fargesia rufa (Green Panda Bamboo). Started with little pots and every year would divide each plant to lengthen 'the wall'. Growing area gets morning sun and dappled midday. It is never watered nor fed.

i dont think 2 nor 3 feet is sufficient for a 12 to 15 foot tall tree ... shall we presume it would be a box with no bottom.. so they can grow into mother earth ???? and keep in mind.. no tree really stops growing at some magical height ... a pic of the spot would probably get you better suggestions ... have you discussed the encroachments with your zoning office?? ken