As far as Im concerned, the usage of "stop" or "suspend" doesn't matter. For our purposes, both of them means deferrals cease when the participant elects to do so. As an administrative matter, I wouldn't start (or restart) deferrals until the participant enters into a new deferral agreement, so stop/suspend simply means stop at this point and nothing more.
Most of my plans are drafted to allow for changes every payroll. I have a few plans that restrict it to quarterly but that is about it. If it makes sense to go with payroll period changes rather than quarterly, then amend away, but you certainly don't have to just because a participant might want it.