Welcome to the published world, Vlada! :)
Yeah - if you ever did want to change your record bit-depth, you would go to a different place in Preferences to do that (you made the right choice by just letting it take care of itself in the mix down, plus changing it to 16 bits would not have affected the already-recorded clips, only those recorded after the change).
Anyways, the place to set that bit-depth is: Preferences>File>Audio Data. Here is the documentation link for that:
http://www.cakewalk.com/Documentation/default.aspx?Doc=SONAR%20X2&Lang=EN&Req=AudioPerformance.08.html (I still don't recommend changing it from your 24-bits, however).
By the way - NICE demo, that was quite intense and creative.
Bob Bone