I just pinched back mine. On lower branches, I pinched back each 'candle' (for arguement's sake, I don't know the exact terminolgy either
) by a third, and each 'candle' at the top of the tree by half.
I don't know if it's possible to overpinch, although I wouldn't remove the new growth completely or work a tree that was sickly.
I've had mixed success too,but from what I can gather they like full sun and a bit of air movement, but not high temps or too much humidity.
There is a really famous twin trunk spruce somewhere-check walter pall's gallery
cheers