Maybe he's a Watcher
In the Dungeons and Dragons 4th Edition book "Dungeon Master's Guide" there exists some very useful advice for running the game that is applicable to nearly every RPG out there. One section of advice addresses different player personalities, including the idea of "the Watcher."
A watcher is a casual player who comes to the game because he wants to be part of the social event. A watcher might be shy or just really laid back. He wants to participate, but he doesn't really care if he’s deeply immersed, and he doesn't want to be assertive or too involved in the details of the game, rules, or story. He enjoys the game by being part of a social circle.
It sounds to me like this person wants to be a part of your group, but doesn't want to get involved in the game mechanics of character creation. Why not make a character for this player, and give them very explicit cues to use that character's abilities from time to time?
Instead of trying to turn the player into something he's not (a better role-player) you might just accept and be thankful to have someone willing to participate and find ways to accommodate rather than educate.
Consider his perspective for a little while.
Most player misbehavior comes from playing around.
A lot of your complaints come from the fact that your player is not taking the game seriously. He is not taking the game seriously. The game is a thing of humor for him. I repeated that for a reason: He's enjoying himself. That's what we tend to do when we play.
Now, with that in mind, let's address the misbehavior:
Clowning
Clowning around is one of the main things that I've encountered as far as issues go. Fortunately, it's not malicious, nor is it particularly damaging. I had a huge problem with this in my first campaign, where I was being all dark, grim, and serious as a novice cyberpunk GM and my players were exploring the effects of their actions on the poor, hapless denizens of the world they were turning into a mess.
This is when they do stuff like buy nine thousand llamas to crash the economy. They're doing it because they can, but they're not ruining your game. My foremost advice when this occurs is to just let it happen. Your player is enjoying himself, and the other players will likely remember it fondly. If you must clamp down on it, be sure to do so with the consensus of other players, instead of just trying to end the "misbehavior" that everyone but you is enjoying.
Redirecting
I've often had players just not be satisfied with the way my campaigns go (and I've been on the participating side of this as well) and decide to intentionally mess with my plot points to redirect the campaign. Ninety percent of the time this has occurred in my games it's been either the result of good in-character roleplaying (for instance, demanding the best gear if the character being played is a greedy, self-serving jerk), or the result of a total lack of interest in the current direction of the campaign.
To deal with redirection, sometimes a soft approach is better. Give your players what they want. Remember that roleplaying is collaborative storytelling, and even though you're doing the lion's share of the writing and creative process you're still responsible for listening to others' inputs when appropriate. Never assume malice when curiosity is just as likely the driving force; I've had players try to kill important NPC's just to see how I'd react, and while it's annoying it's also a way to prove yourself as a good GM by reacting prudently and without exploding (though specifics depend on you and your style).
Trolling
Sometimes players troll you. They'll lock all the other players' characters in a bomb shelter, but reinterpret the meanings of the phrase to result in a deliberate invocation of the "chunky salsa" rule and make everyone re-roll their characters following some explosive goodness. This is usually the result of a player who's bored, discontent, or offended in some way and wants to make the campaign more "fun", perhaps at the expense of everyone else.
The important things to look at when dealing with a troll are rehabilitation or removal. Sometimes it's enough just to ask them to stop, politely. Don't place a "red line", either. It's a great way to get a player to quit in a blaze of glory having killed everyone else's characters. Other times you need to just ask a player to leave temporarily or permanently because their behavior is just so disruptive, but this should be a last resort following other remediation (i.e. the one-on-one chat). Manage trolls privately, not in front of the rest of the group.
A closing note:
One thing you may need to do is set guidelines for your player. If they're constantly playing the same character's mindset, but just remaking them according to different rules, you may need to set boundaries and restrictions on them. Consider very carefully that your player sees things differently than you do; if he doesn't know where things are going, he may very well be disruptive without knowing it.
Also remember that he may be playing the villain in lieu of your NPCs; I've seen this happen multiple times in my group because one player or another doesn't think that the core conflict is interesting, and injects another one to the group dynamic just to liven things up.
If you don't read anything else, read this: Get in your player's head and talk to him before taking any action, communicate your concerns and expectations, and be prepared to use in-game consequences or removal from the group only as a last resort.
Best Answer
In situations such as this you have a few of choices.
Gygax used to do the third one quite frequently actually, side conversations, especially in delves and wilderness excursions were treated as in character at all times. So when his players were joking about the hirelings as nothing but fodder and a few died the role-play digressed into negotiations for resurrections and the like.
Bottom line comes down to if none of these work and he continues to be a disruptive influence you should talk to the other players about possibly removing him completely from your game. I know it sucks but 4 people's fun sort of outweighs his in the long term and voting him off the island, as it were might be the only option after all others have been tried.