Some questions,please help:-)

[Diego2812]

Hi everybody,
I'm new here and i need answers for this questions:

1.When you send request to any actor/actress which address is the best to use "fan mail address","secondary address" or "via venue address"?
2.Should I write my address on the envelope?near celebs address?or in a letter?
3.I don't understand IRC's,where should I place them?inside envelope?and how many should I purchase if I want to send letter to USA(I'm from Poland)?
4.To send request is enough envelope with stamp?

Sorry for grammatical errors(if they're),but I'm learning English,I'm not very good yet