#1. Select all tracks you want to operate on - activate Quick Link(I think mixer toolbar) - then disable send on track, and the others should follow.
So this was a quick link group you made. Q-Link can also be assigned a key command.
I tested - this works.
#2. To automate this selection - a series of operations can be made into a macro
Project Logical Editor can select tracks based on names - if you have a system how you name these - that part of name can be used.
This can be made into one row of your macro. Condition may have OR-statements so several naming conditions can apply - and they are selected in one go.
Q-link toggle can be one row - but it toggles - so need to be in the correct phase, kind of.
So if part of macro - it might need one or two activations - depending on current state of Q–link.
So connect this macro to a key command - and have them done in a flash - at least.
But disabling/enabling midi send - I see no command for that. When disabling entry becomes blank, no text, but it seems to be there if you enable again.
Closest I saw was toggle the send section itself in Inspector.