How to jungle effectively with Wukong, using its decoy ability?

Solution 1:

Jungling with Wukong became a lot harder with the introduction of the new jungle. He didn't have the fastest clearing speed before and now he even has some trouble with the incoming damage (and the camps also recieved a HP buff).

All this makes a correct usage of Decoy important. Note that jungle Camps always focus the closest unit if they are in combat. Because this your best chances of getting the jungle creeps to focus your clone is by simply walking as far away as possible. Using your E will teleport you into the targeted unit which automatically makes you the closest target so try to use your decoy after your buff from your E ran out (you won't lose any attacks on the creep like this).

Keep in mind that the current Summoners Rift map is still in beta and I've seen a lot of jungle minions bugging around.

For your second question: Usually you should go with E -> Q -> W for more damage output but taking W second also works as a tiny survivability boost.