I'm a left handed guitar player, and I feel your pain, I hate not being able to find left handed guitars, shops around here hardly stock the ones I want. As for riffs, I'm more of an improviser, mostly because musical notation annoys me, and partly because I find it more fun. The first song I tutored myself properly was The Killing Hand by Dream Theater. It was a fun song to play and it is quite an accomplishment learning to play a long song. In terms of fun riffs to play I'd recommend all the usual bands: AC/DC, Iron Maiden, Pearl Jam, that sort of thing. They have lots of awesome riffs to learn.