Update on previous post, but still need help identifying "hissing" source and determining if level controller and/or strut/shocks are ng?

* If one accumulator is bad, should I replace the other as well?
Yes, replace both.
* From underside, there appears to be 3 nuts securing the accumulator. Or is there something else securing it?
Just 3 nuts and the hydraulic lines.
* Left side is reasonably accessible, what's the secret to accessing the right side?
Knuckle buster. Maybe disconnecting level controller from its mount.

"Sea foam" appeared while R&Ring fluid, so at least one accumulator is bad.

Rear is supposed to be 1/2" lower in rear. Mine is, but so is left side of car! Ideas?

The door locks work well, but could the "hissing" noise be comming from a vacuum leak?

This all started when I realized on my 94 e320 Wagon, the rear suspension didn't automatically go up or down. And the rear mounted CD player skips a lot more than before. I've never ridden in another Benz, so I don't know how it's supposed to ride/handle. To test it, I had 5 college students in the back. Didn't move.

Suggestions are appreciated.

Bob