I used baby gold and red potatoes which will have a creamer and starchier texture
For more traditional mashed potatoes you may want to use russet potatoes and adjust ingredients as needed for texture desired
Plan around 1/2 of raw potatoes per person when planning how many mashed potatoes to cook
Leftovers should be cooled completely and then can be stored in airtight containers in fridge up to 3 days or freezer up to 3 months