I believe that the XY_TRAVEL_SPEED setting in the Configuration.h file is the maximum speed allowed, not necessarily the common travel speed. The movement speed would be defined within your post processing.
As for the homing issue, that is correct. The homing function, G28 is homing in the -‘ve direction until it hits an endstop. You are probably looking to just go to your programmed 0,0 so try : G0 X0 Y0