Re: Help with chords on a mode ?
It's kinda a common misconception at first, when you start getting into them - you don't just write a progression and say, "ok, I'm going to play a mode over this," because that implies that a mode is somehow different from a scale. It's not - it's simply a way of understanding scales as inversions of themselves, so to speak. the same rules apply, in that the chords you are playing over dictate the tonality of the peice, and in turn the scales you choose.
The progression you are soloing over happens to have a strong C Ionian feel to it. Thus, the most logical and "inside" sounding scale to play over the whole thing is straight-up C major. If you were to try to play C Dorian over it, for instance, you'd have a LOT of notes that didn't sound very good. If you wanted to play something in dorian, then you'd need to play over a set of chords that work with the dorian mode - say a sort of bluesy Cm-F-Gm progression.
does this make any more sense? A mode isn't just something can turn off and on - "Ok, now I'm playing modally. Ok, now I'm not" - because modes ae just scales. It just so happens that they can be understood as inversions of a major scale (i.e - dorian is a major scale played from 2nd to 2nd), but at the end of the day, they're just scales, and they're no different from any other grouping of notes, in that you have to choose them to correspond with the chords you're playing.