Okay, after tinkering with this for a little while, here's what I've found:
If you push 'a' your character will go into autoattack mode, where they automatically approach and attack enemies within their line of sight, so you can do that if you don't like to mash the directional keys.
When you drop items in the store, you don't sell them so much as you put items up for sale. You enter the price you want and another player can purchase it for that much. If you sell an item for $0 it will be unbuyable, so essentially that will make it a stored item you can come pick up later. This is good, because you drop all unequipped items where you are standing when you die.