I have sonar 8.5 as well and soon to upgrade to x3 studio, which has melodyne essentials, which might come in handy for some of the loops as well.

I may be overly excited about 2014 but it looks open ended as far as what I can envision.

I'm thinking that the playing of the fill part might be to create a user track called "fill" then at the bar select a part marker that plays that user track.

Just guessing, I just have to get some time to learn all of this.
Wyndham