R.,
Just a few things came to mind, the more I typed the more I thought of...
Positive reinforcement!!!
It sounds like he picked up a lot of bad habits at pre-school and he probably is bored. Anytime he is behaving appropriately, reward him for it! Use his name, say exactly what it is that he is doing right, and tell him something positive about it (R., Thank you for carrying your plate to the sink, that is very helpful, thank you, ...) You don't need treats or prizes, just mommy's attention when he is doing what you want him to, or he'll get your attention another way, negatively. If that doesn't work, start a calendar, he gets a star for everyday he goes without...sticking out his tongue??? and after so many stars he gets a tangible reward, McDonald's for lunch, the zoo, what ever is appropriate for the behavior, start small, but with something he wants.
get a playdate set up for one or more of his friends from school, their mom's are probably going through the same thing
school is structured and they have jobs, give him jobs to do, structure his day atleast a little.
I have also found w/ my 2 young ones that 15 minutes of playing with Mommy, gets them playing and then I can get stuff done wihtout the negative, attention seeking behavior.
good luck!