You've got more fermenters than me now, mate. I might have to take myself down to Bunnings after voting tomorrow, just to catch up!
I've used both brown sugar and coffee to brew with. The trick is moderation. With the coffee, try adding a tiny amount to a glass of beer (the finished product) and then keep upping the quantity of coffee you add to each new glass until you reach the taste that you're looking for. When you've got that number, it's just a case of multiplying the amount of coffee you used by however much is needed to compensate for your whole brew's size.