We already have Masters hosting tournaments
Seriously though, I wonder whether you either imagine these to be held seperatly from current tourneys, and be just for fun, or to be held collaboratively with current tourneys, that tourneys be focussed around that element once every other week (it's not like we have too much ideas for current ideas) and that the rules are discussed between the Master of that element and the TOs (TOs have more experience with tourneys than the average master : P). Another fun thing would be to hold some giant pvp event, focussed around one element, with a nice icon of your element as reward or something (I want them already, lol).
Not sure what to think of a deckbuilding competition, all kinds of tough details involved in that, primarily where do you want to judge a deck on? Of course, playability and creativity, but there're just so many factors involved in deckbuilding.
I'll let people who know more about the other parts have their say about those
I say elements have to be picked by rotation, not by popularity, but that's just me.