Thanks that's a really handy guide, I also like the Social club, seems really detailed. When I did my hat shooting in Multiplayer I went to Tesoro Azul (sp?) gang hideout where they all wear sombreros, I think for the shooting 2 hats in 5 seconds, I just shot the edges of the hat, like, the rim, think I'll try that in single player too.
As for disarms I have real trouble doing those reliably, and I see myself struggling with the 6 disarms without reloading but my plan was to just use the Mauser pistol and go around disarming random enemies one by one.