I'm trying to figure out what is the difference between a straight harp and a cross harp, what exactly is a cross harp? Please help me if you can, thanx.

Straight Harp and Cross Harp have to do with how the harmonica is played. If you play in straight harp (or 1st position), you are playing in the key of the harmonica. ie: Playing a song in the key of C on a C harmonica. Cross Harp is playing in 2nd position. I don't remember exactly which key you'd be in on a C harp, but basically you start on draw 2 (or blow 3). Perhaps others can give you a better description than me.