An average non-self defrosting chest freezer will take 6 months to use as much electricity as your average frost-free refrigerator uses in 1 month so energy use of a freezer is not nearly as important as that of a refrigerator.
There are no major freezer manufacturers left in the USA and only one that I know of in Canada and the rest are made in Asia.
Lowes and many other stores sell "commercial" models that will go down to -25 degrees.
Definitely the case. Also running a full freezer costs less than a nearly empty one, even if you just use gallon water jugs for fillers. Frequent opening of the door adds more cost. Being excessively cheap, I'll take out several meals at a time to put in the top chest of the fridge; by opening the freezer once a week I barely notice it on my power bill.
One last suggestion; I have the sensor from an indoor-outdoor thermometer in my freezer. Ican tell at a glance if it's working properly, which has saved me a couple of times when the freezer failed.