As for the ccs: Did anyone try to stack cc reduction on gear yet? This could be a highly valuable stat in a pvp situation (obviously only for complete player choice gear). Also, certain passives could be quite strong, for example Pacifism with its 75% damage reduction while cc-ed or Juggernaut with a chance of a good amount of heal. Not to mention that each class has 1-2 spells to break or ignore ccs.
Don't get me wrong, stuff like Hex might still be horribly imbalanced. But maybe its not that bad on a Monk with maybe 60+% cc reduction (I assume thats a reasonable amount if you stack it on a couple of items), pacifism and serenity. Instead of being perma-hexed, he is only hexed 40% of the time, takes only 1/4 damage while being hexed (assuming Pacifism works on Hex) and can break free from every 3rd hex, doesn't sound all that imbalanced on paper.
Pardon me while everyone specs out their characters to specifically deal with Witch Doctors Hex. That's not broken at all, right?
When it comes down to it, some skills just have to be banned. The game was designed with PvE mainly in mind, and that causes great imbalances in characters when they are actually pitted against each other in combat. Hex, as mentioned above, is one such skill that needs to be removed in this case.
Also, you might want to look into banning some passives. I can't think of an example right now *cough* Fierce Loyalty *Cough*, but I'm sure it would be worth looking into.
As for potions, I guess I don't really see the big deal with them. Like the OP already said, they have a large cool down on them, and if you are geared out a lot with a lot of LS/LoH, etc, they won't make much of an impact on anyone since the strongest potion heals only 12,500 I think, a number than can be destroyed in a second or so. I say just let them be.
This is more or so preference, but I had an idea for a rule-set concerning gear restrictions:
White League: Players may only use grey-white items. Blue League: Players may only use magic items. Yellow League: Players may only use rare items. Legendary League: Players may only use legendary or set items.
This would allow players to basically filter the sort of items they would be using, and I personally think it would be interesting to see players using strictly legendary items only or full item sets for once.