2 things to do/not do in my opinion.
1.) Do not buy a mora if youre going to connect to a cordless drill. Yes it will eventually drill through the ice, but your drill is going to work a lot harder to do so. Which means you will get less holes/battery.
2.) A lithium ion battery is going to be your best bet when choosing a battery/drill. All batteries drain fast in the cold. Lithium batteries dont have battery memory, which means its not bad for the battery to be completely drained before bieng put back on the charger. Its actually better for the battery to be "drained" down to zero.
If you are going to use an 8" auger, you better have a hell of a drill. Most drills will turn an 8" auger, and again YES you will eventually get a hole drilled.... but if you want to maximize holes/battery go with a 6" auger. Ive pulled some really good pike thru a 6" hole. Im not saying its the easiest task in the world.... but its do able.
I personally use a 36 volt Bosh cordless hammer drill with a 6" strike master lazer auger. Ive drilled through 32" of ice with this combo. The strike master lazer is the key to the combo. If i hadnt spent so much money on the drill, i probably would have bought a Nills auger instead.