I just picked up a copy of Warplanes of the Future (about $7 used). The section on the "Stealth Trimaran Aircraft Carrier" gives a few more details.
The diagonal flight deck is said to be 450 ft (130m) long, which makes the overall length about 920 ft (280m). Displacement was reported as approximately 40,000 tonnes, with a capacity of 55 aircraft.
As speculated, exhaust would vent between the center and sidehulls. Speed was to exceed 40 knots, but no other details of power levels or prime movers was mentioned.
Launch arrangements are confused. In one place, it mentions an electromagnetic catapult on the port sidehull for launching aircraft like Typhoon, Rafale, and F/A-18E. However, measuring off the drawing shows this catapult track to be about 130 feet long, which is only half as much as a C-13-1 steam catapult. It's hard to imagine that an electromagnetic catapult could do the job in half the length, even with the smoother acceleration profile it offers over steam. Elsewhere, it mentions the projectile-based catapult, with drawings suggesting it would work along the angled ski-jump.
The various dark spots along the hull seem to be phased array emitters of various unspecified sorts.