Someone sells an aluminum luggage block which can probably support a heavy front bag. I would get that and just pack a camelback and everything in a sturdy bag. All that weight is on the frame not the steering so should handle better.
I have a carbon seatpost on my Dahon and it always slips down even with carbon paste and a sanded surface. I would research if the same problem exists with Bromptons or just stick with a ti post.
Litepro and Extralite makes light brake levers that would fit a straight bar but they don't fit well on an M bar.
Clavicla is the lightest crank but I would be wary of carbon cranks on a world tourer so would look at Hollowgram or NextSL Cinch cranks.