It is not a juniper. It is a Dwarf Aberta spruce, and quite old, 20-35 years old depending on what part of NY this is in.
This is the natural overall shape of the tree, and it looks to me like the previous owner just shoveled snow from the deck/stairs that created the big open spot near the bottom mostly by yearly bending and smushing the branches that were there. There aren't enough dead branches there that that would have filled that space.
I don't see any salt damage. That would have shown up in the spring, not late summer. Or, the problem would show through out the tree if it was severe, and not in just a few places.
The dead branches on the deck side of the tree died from insufficient light. The other stuff that died and is dying seems more like a fungal problem on the needles. Cleaning out all the dead twiggy stuff should help to increase air circulation and naturally curb the problem. But it will have no effect on root rot. I don't see any indication of root rot, anyway. The tree species is native to a much drier climate, and more importantly, a climate with drier air. There is not much you can do to mimic that, except try to keep the free moisture from lingering by improving air circulation and decreasing dead air space.
Daisy is right that new growth will rarely sprout from the non-green twigs, even if the twigs are supple and alive.
I would not fertilize the tree now, this late in the season. But do think about it next spring, when new growth on the tree begins.