I've always just used a regular 8x10 or 9x12 envelope for sending overseas, and I've never had a problem. I usually send 2 IRCs if I'm sending one or two 8x10s.

Hope that helps a little...I can't answer your other questions, unfortunately.

Hi all!

I am going to send an 8x10 photo from the US to Australia.

The person I want the autograph from is not a very established actor. I'm not sure what their talent agency is. But I do know what their modeling agency is because they are an established model.
Would sending to them through their modeling agency work too?

I am not sure what kind of envelope to use... I know it has to be international. But aren't they cardboard? How do I fit a SASE inside??

I think I need to get 2 IRCs. Is that right?