I'm about to hit the sack, been watching the MotoGP and will answer properly in the morning, our time, but the bottoming is a spring rate/travel issue and the ARB bushes flogging will be more than likely from the extra travel with the dampers allowing the links to try and invert, which will really squeeze the rubbers.
If it's not riding properly you do need the dampers to match the spring rates, the adjustments usually only work on the low speed circuit of the dampers (unless they're triple adjustables) and the adjustment is only for a relatively narrow range.
Usually any more than a 50lb rate change from what they are designed for and the dampers need re-valving.

