Boony,
Straighten the disc mate. Just spin the wheel and measure the points where it starts deflecting against a fixed point (say the swing arm). Then get a shifter and put it in the middle of the bend and straighten.
As for the solid discs. I actually heard they give you better feel. My mate swears by them. They wear your pads out less as the pads are rubbing against less edges (ie the edges of all the little holes). As for stopping power they would be exactly the same. Friction is not dependant on the area of contact but the force applied to the contact which is exactly the same. At the end of the day you only need enough on the rear to lock it up and as soon as that happens the tyre/ground is the weak link.