as greene said, that leafy growth at the base is most likely from the rootstock. You should prune it all off.
I would wait a few more weeks, and see what sprouts from the tops of the trees. Definitely do not cut anything off unless you're sure it's dead wood (except the rootstock suckers) though. Those little trees are going to need all the leaves they can muster to get going this spring.
A better way to find out if the tree is still alive, rather than breaking off a twig is to just scrape the bark in a tiny area with your fingernail. IF there is green under the bark the branch is still alive.
As soon as you see new leaves open, give them a light sprinkle of fertilizer, and make sure they don't get too dried out.
Btw, would you please complete your personal profile to add your location? Knowing where you are makes it a lot easier to answer questions in future. The personal profile icon is the little person at the top of the blue sidebar on the left.
