I'm planning to send a request to an American actress. I'm going to send her pictures and a DVD cover to sign, so I need a big envelope. I'm going to use one that is a little bigger than a normal DVD.

size about 16,2 x 22,9 cm (c5)
How many US-stamps do I need for the SASE (USA to Germany)? I was thinking about 2-3 dollars, is that enough? Please help!
Also, do I need to put an "Air Mail" sticker on it (as I usually only use small Air Mail envelops and I've never tried bigger ones)?
I really appreciate your help! Thanks
