Best Storage:
Cool place
Store in cupboard.
Keep away from onions as they both release moisture which causes eachother to sprout. If your potatoes do sprout, they are still ok to eat, just push the sprouts off or plant these sections in the garden to try growing your own.
Freezer?
Yes
>> Only cooked potatoes can be frozen! << Cook and store in freezer containers in meal portion sizes
Use it up!
Use up extra mashed potato to make cheesy mash potato frittas or make some yummy mash potato balls! Add some leftover veg or meat, roll into balls, dip in egg then breadcrumbs and fry until golden. Fried mashed potato balls: