This week's challenge is Overcoming Attitude in a 4 Year Old

Manifestations of aforementioned attitude:

(1) Saying HUH when asked to do something (followed by the requested task though)
(2) Stamping of feet
(3) Hitting mum and dad
(4) Case of the I Wants
(5) Repeating phrases from Ben10 like "I'm so outa here", "I'm so over this" and "Will you guys just leave me alone"
(6) The usual whingeing and whining

Locations of aforementioned manifestations:

(1) With his parents
NOT with any other person (ie Mungles' mum and dad looked after him today and said he was well behaved all day)

Possible causes of aforementioned attitude:

(1) Watching too much Ben10: Alien Force
(2) Holiday and being spoiled too much by grandparents
(3) Still being tired after school (he has been full time from day 4)
(4) Being nearly 5
(5) All of the above

Plan of action:

(1) Conkers - a conker is added to a special jar when Elf has been good all day, and removed for a naughty act, a full jar resulting in a reward
(2) Only one episode of Ben10 is allowed each day
(3) Harsh but fair - just now is a good example - Elf wanted a bit of paper, I didn't do it quickly enough so he bashed the table. Now he won't be getting a piece of paper
(4) Ask my lovely readers in the blogosphere for help (I had great help on the issue of guns a while back - thank you)

My questions to you are:

(1) How much of this should I accept as just expressing himself?
(2) When will he grow out of it? (On second thoughts don't tell me the answer is 16!)
(3) If he doesn't do it to other people, is it just that we bear the brunt of it?

Any help will be thoroughly welcomed!