Help with choosing and using a MIDI controller for writing mix automation in Studio One and DP...

Hello Everyone.

I think I need a controller for playing/riding automation curves whilst mixing. I use Studio One 7, DP, and Ableton Live. I will mostly be mixing in Studio One, however.

I believe the process is to MIDI assign the controller to a parameter, like the send of a track, and once «connected», it will be able to control that element. This is clear to me.

My main question is: If I am mixing a track and want to control the reverb send, I go ahead and connect the MIDI controller to that parameter (ex: a fader). But, when I want to next write automation to control the delay or any other FX send, I will need to disconnect from the reverb send and then reconnect to controllers' fader to the new send I want to control? Is this the way it is done? It seems really cumbersome to have to do this for every parameter, and in some DAWs it is more of a PITA than others!...;-) Am I understanding this correctly?

Second question: is it best to get a controller that handles a single channel, or one that does more at the same time? It might be nice to ride group busses, or vox and solo instruments at the same time?

For the controllers that do more than one channel at a time, do the channels you control have to be next to each other in the DAW? I often group things not next to each other in my mixing layout... Does this make sense?

What is the general sense as to which controller would be the best way to go at the moment?

Thank you for any help and insights, I appreciate it.