To stop the eating too fast, you can put his food on a cookie sheet with sides so he has to work a little more to get it. I know someone who this worked really well for.
may I ask how you would know if its a hairball my kitty has been heaving a bit this afternoon and spitting up bits of food .
I would first ask you, do you brush your cat's hair regularly? This could be a problem caused by a hairball. Or, go to the pet store and buy cat food that is specifically for cats with a digestive problem. I would also schedule a vet appointment.