Put a quart jar of warm syrup inverted over the inner cover hole and put an empty super on top of the inner cover and then the top cover. If the weather doesn't warm up enough during the day, give them warm syrup each day. Keep two jars and swap them out.
Don't feed sugar, you are just making it harder for them.
If you mean a 5 frame nuc vs. 10 frame deep, the nuc would be best and do the same as described above.
They have no brood to take care of so they can cluster as tight as they need to keep warm. They will most likely cluster right under the jar and will keep it warm.
I have installed packages in the middle of a blizzard and they survived fine.
Like this, but with a normal super, not a vented box.
BTW, where in NY are you located?