I'm wondering whether I can have the knobs/sliders controlling parameters of more than one instrument and effects at the same time.
For example can I have a knob to control the cutoff of ES2, the one next to it to affect the delay of another instrument, and each pad to generate a different instance of loopback/playback etc.
Or im i necessarily restricted to the mode/instrument that i have selected?
No. You can tweak controller assignments in very specific ways in the Expert View window:
And if that is possible, can i have multiple 'banks' on my controller surface each one having a completely different set of such assignments?
I think you can, yes, with modes and zones. I just have no personal experience with that yet.