I appear to have figured out PART of my problem: that of not being able to attack creatures without using an ability. It seems that, whenever I tried to rebind my attack back to Mouse 0 (which I attempted to rebind to Mouse 1, initially), it would automatically remove the binding after I left the menu. However, if I clicked on Attack first binding field (to rebind the button), then clicked on the SECOND binding button for attack, it would stick. That was weird as all get-out to figure out. Essentially, it wouldn't let me rebind the first attack button if I clicked anywhere but the SECOND attack bind button AFTER clicking the first. Ugh. That all said, no other keybinding FOR attack worked, either. It has worked after I figured out how to actually rebind it to Mouse 0, but as soon as I try to make attack anything other than Mouse 0, it stops working.
However, auto-attacks still don't appear to work unless they are attacked- they won't if I use an ability, which makes it incredibly tedious to manage everyone (though it's easier now that I actually CAN attack again).