Fairlight-CMI

Bear with me here, this is where my absence form playing keys is
going to  show.  I want to compose a piece using several voices. play it into
page R and at some point mix it down onto tape with more voices and
ornamentation.  

To do this, I need to create a System File with the required voices & settings.
Right? I've  got a system file containing KitLive11 and Piano Rock11 with
Choirmale13.

So far, I've managed to get a pattern in Page R. Now I want to
improvise to see what I can come up with while this rhythm is playing.  When I
play the piano part, the sequencer is also triggering the drum sounds. I ONLY 
want the kick drum and a Mid Tom from the sequencer while I play the piano 
part over the rhythm live.

My question is...HOW do I map the 2 drum voices to, say, the lowest 2
keys on the CMI leaving the remainder of the keyboard available for the piano
voice? 

Do I go into SC and map the keyboard there? I tried and I still get
both sounding together OR do I do this all with MIDI channel mapping?

Aside from this, after I get a piano groove going, I may want to add
ChoirFem to the project for ornamentation. ChoirMale I'd like to use as a bass
line in certain sections.  I'm just unsure how to go about all of this. My
experiments have led to frustration. 

Or, dare ask, am I asking too much of the CMI?  I don't think so
after hearing some of the things I've heard done with it. Or am I going
about this all wrong to start with?

Any advice greatly appreciated!

Thanks!!

Jerry