1. Getting them out can be done with hammer, chisel and brute force. Not
elegant, but effective, as you don't need to preserve the bushes. Getting back
really requires a hydraulic press. It could be done with a hammer and tube,
but you risk damaging the bushes. I'd use a lick of grease to help insertion.
2. RHD to LHD can be done with existing equipment, apart from the steering
box and idler arm, with I believe are handed are handed. You may be able to
retain the box itself, but certainly you'll need to change the arm at the
of the box. You'll also need to move across the handbrake, and I think the
cable length is different. You can use the same master cylinder for the clutch,
and possibly the brake, but watch out for the brake unit, as some designs could
foul the carbs, if you have Strombergs.
3. The UK suppliers usually stock the necessary bits for the soft top frame.