At 300 AD per Zen (which I think is a lowball estimate), 4000 Zen is 1.2 Million AD. I've been leveling Leadership with my main character and doing a few dailies here and there and I'm at like 50,000 AD total. Granted, you can make 24K per day, but that would take massive amounts of griding or working of the AH. Even if…
It seems like in all cases with Leadership, the longer tasks are significantly worse as far as bang for your buck goes. That said, I agree that rare tasks should actually provide some kind of incentive to use them besides going to bed and needing to blow 8 hours on a task. I'm having a way easier time leveling Leadership…
The filters don't seem to do anything on the Gateway, at least for me. I check "hide stuff I can't craft" and it shows everything anyway. And stuff I should be able to craft is red. But I found if I click details (where continue is if you can craft), it opens up and I can craft normally.