Trees go through a process similar to hibernation called dormancy, and that is what keeps them alive during the winter. Dormancy is like hibernation because metabolism, energy consumption and growth within the plant slow down.
This is an interesting little video that explains how your trees survive the cold we are presently experiencing.
October is also a good time to get deciduous hedges and those big trees pruned before the winter gales.
Well, yes and no. It depends.
Young trees, whether planted by you or by your municipality need lots of help to get established.