With butter, I'll go with regular; without, sweet.
How many potatoes with the beer
Depends on your goal. For the average drinker 2 potatoes per 24 beers is enough but for the out an out alcoholic who needs more energy for battering wives etc 5-6 potatoes with 48 beers is the norm. A light warmup of whiskey is recommended. Stretching before hand is also a good idea.
sweet potatos with a little lots of butter, equal and cinnamon
Sweet Potatoes do not spike up your blood sugar as the white ones do, much better for you. Pretty much any white flour, rice or potatoes will raise your blood sugar just like candy would.
Sweet potatoes also higher in potassium, which is not necessarily a good thing.