xdistfrommidpoint = radius * sinf(rotation);
ydistfrommidpoint = 0;
zdistfrommidpoint = radius * cosf(rotation);
cameraxpos = xdistfrommidpoint + midpointx;
cameraypos = ydistfrommidpoint + midpointy;
camerazpos = zdistfrommidpoint + midpointz;
and voilà, you have your camerapos, and your target (midpoint)..
hope that inspires you..
oh, and math is the most important thing in graphics, quick! catch up! vector math all the way! its not much actually..