Oh okay, if there is no setting available to stop that resummon of companions I'd say best would be to rage about that in official ESO forums and ask for a setting for that in the vanilla game settings first. I second this for sure.
About the 100 possible changed keybinds:
Every changed keybind, no matter if vanilla game keybind for gamepad or keyboard (e.g. change keybind for "use" to something non default -> -1 custom keybinds), or an addon added keybind is defined, counts as -1 custom keybind!
Even not currently active keybinds of addons still count as -1 once they are set.
https://wiki.esoui.com/Keybindings#Keybind_facts
So if you want to free up those you should enable all addons to see which keybinds got changed, then unset the ones of addons you do not use (anymore)!
And also change back the vanilla keybinds to defaults for the ones you do not use.