EXS 24 Logic Sampler Users Group

I'm quite fluent in Logic, but mainly on the audio side. Recently I've
been getting into the EXS, and I'm digging the possibilities it has.
And I have two questions for you guys who know it well.

1). Sidechain. I'm able to get other audio instruments to work in
sidechain mode (like Zebra, for instance), but haven't been able to
figure out the proper combination to get it to work in the EXS. What
do I need to change in the Matrix to get this to work.. do I have to
set up anything new in the matrix, or simply change existing Sources
to Sidechain? Any quick turorial pointers would be greatly appreciated.

2). I'm using a D50 as controller at the moment. Every time I RELEASE
C#3 on the D50, it puts Logic into External Sync. It doesn't toggle
the sync mode, but just turns it ON if it's on Internal. I can record
a sequence, including the C#3 which will turn External on, but when I
play the sequence back, the sequence itself doesn't do this.. it's
only when it is played from the controller. When I look at the
recorded events, all that I see is a Note Off.. I'm quite confident
that I've just got something set up improperly, but being new to the
whole MIDI thing, I can't figure it out. 

Thanks for your help!
Cheers.
jb