EXS 24 Logic Sampler Users Group

Hi there.
 
I recently got the exs24 and am quite confused. I would like to be 
able to load 2 exses and play them simultaneously. However, only 1 
will make sound at a time... that is, in the arrange window, only the
*selected* audio instrument will output sound and I cannot select 
multiple audio instruments. I'm sure there must be a way to do this 
that I'm not getting. I'm using logic 4.8.1. 
Also, is there a way to have the note sustain in the exs so that 
when  a I trigger a sample (and have it set to loop) it will loop 
without me having to hold the key down? So far, I have to physically 
hold the key down for the duration of time i would like it to 
play/loop.
What  I want is to be able to press the key and have it loop for the
number of loops I specify. I am hoping to use this setup in a live
setting, so triggering clips live is what I'm after.
 
 Is this a reasonable expectation?
 
 I truly appreciate any light you can shed on these matters.
 
 Thank you,
 NomIg.