I think for the most part this is clear, but let me re-iterate in my own words to see whether I'm just under a delusion of knowledge.
the song is in C. I encounter this chord : Cmaj7(#11). upon seeing that, I start to solo in the lydian mode, which in this case just means playing C major starting on F. is that about right?
also, upon seeing this chord, I do various fancy things. then, Dmin7 comes up, and I play around, ending the bar on an c, and then going down to an Bb at the beginning of the next bar, which works because the next chord is G, and this is a ii-IV progression. is this kinda right? or are there some holes?
also, I was in a sort of workshop setting with those guys. Alex Dean did master classes in the Morning, we broke for lunch, and then I went to my ensemble, which did a bunch of tunes. Mike and Dave lead the ensemble. repeat this every day for a week. it was awesome. it was done in a highschool, though...
so it's combination