Re: air cells/ accumulators
The full procedure is detailed in the chassis manual. If you've already replaced the struts then you know to release the pressure in the system. After that you just remove and replace the spheres. The spheres will most likely be full of hydraulic fluid so be prepared for a mess. Drain the storage tank in the engine bay and refill with fresh fluid, be sure to get the right stuff. To bleed the system, start the engine and ask a friend to bounce on the rear of the car. Keep an eye on the fluid level and replenish as necessary. The experts can fill in any of my oversights, but that's about it.