Do they sell by the case? 12 pack? 6 pack?

When they have cans, it's usually 4 packs as their cans are 16oz. There may be limits on how many you can buy, usually in the range of 4-6 4 packs

What was answered was right

They usually have about 4 different types of beer canned

4Packs of 16oz cans with No Limit on quantity

They sale by 4 packs. But you can by a case if they have enough.