Slightly less basic Marianas Trench info?

     I've been poking aroudn the internet looking for what I'd think is pretty
straightforward information... how deep is the Challenger Deep?

     Yes yes, it's 7 miles from sea level... but how deep is the surrounding
ocean floor?  How deep an 'indentation' is it compared to the nearesat plain? 
One side of it is a continental-ridge-thing, on the west side?  So what's the
ocean depth to the east of it?

     Also, kindly correct me if I have this wrong... the trench is 150km (mi? 
crap...) long and 10 wide.

     Uh, no fish sightings below 5.2 miles sea level...
     Was there some vent activity in the trench?  Where (what height) was that
at?  The vent had the normal gaggle of deep-sea hangers on, yes?

     Hope someone here has the patience to answer some of my questions, the
general bio's of the trench don't seem to give more than it's beauty
measurements, I want to have a real picture of it in my mind.  ;)

     -Derik
     "I regret to say that we of the F.B.I. are powerless to act in cases
of oral-genital intimacy, unless it has in some way obstructed interstate
commerce." - J. Edgar Hoover

     I want an expansion team named the California Wildfire.