It's an engine, not a child. Cold weather will not hurt it. Antifreeze will stop the block from cracking. Hood insulation was discontinued, then started being standard again on certain models. My Unlimited Sahara has a build date of 4/07 and has the hood insulation. I think it is mostly for noise. It also stops the outside surface of the hood from getting as hot with the engine running. It does nothing to keep the engine warm in the winter when your Jeep is sleeping outside. An engine block heater may be useful in extreme cold to assist with starting. You can get them at the dealership if you don't already have one installed.
2014 Copperhead Pearl Unlimited Sahara in progress