Hi Kevin;
The LCD panels you are referring to are a status display only kind of thing. There's no user interaction possible with them, so they will not directly provide you with the flexibility to do what you are wanting to do.
You are going to need an LCD screen with a touchscreen overlay, or a tablet computer, or if you are determined to use the type of LCD display you mentioned you'll need a bunch of extra physical switches in your console connected to the MIDI encoder.
I did a project similar to what you are proposing but I went after the MIDI Play/Recorder, the Pitch Menu and also created a status display screen (expression/crescendo pedal position indicators, memory level, SFZ indicator). This involved enabling MIDI output from Hauptwerk (page 34 & 222 in the manual) and writing a bunch of code for an Arduino microcontroller.
I haven't attempted to answer your actual questions, I'm just trying to point you in the direction I think you are wanting to go based on the first sentence in your post.