I purchased a Mazda 2 2008 (gas, not diesel) and would like to import it to the USA. I need to know if it has a catalytic converter and if it will meet the EPA standards.

Where are you at?
Does the car run on Unleaded Gas?

I am currently in Guatemala. The car does run on Unleaded Gas. It is the 1.5L model, I am curious why the USA hasn't imported these smaller cars previously?

Ford and Mazda are supposed to be bringing it in next year.
As for the Catalytic converter, if you run unleaded gas it should have 1, but I think you could ask at your local Mazda Dealership also.

I need a letter from the manufacturer's US
representative declaring that the specific Vehicle Identification Number (VIN) was
manufactured to meet EPA & DOT standards. Any idea where I might find a US representative that can write this letter for me ?

You might try going to Mazda USA http://www.mazdausa.com/MusaWeb/contactMazda.action?bhcp=1

You will have to specify what state it will be registered in; California cars have different emission control systems (and norms) from anywhere else.
You could also have it emission tested and certified by a Mazda dealer in Guatemala before starting the red tape of US importing/registration, because it would a bummer if it didn't meet US norms and you had to unload it after arrival.