Manual Cue Timings

(On an Ion) I have cues that have focus time set to manual, so that with moving the fader I can essentially followspot a performer using that fader - I was just wondering a couple of things.

Is there a way to make the master fader for that cue stack work in both directions (ie For cue 1 I can push it from 0 to 100 to manually control the focus time, then for cue 2 I can push it from 100 to 0 to control the focus time?) rather than having to bring it down to 0 to reset it for every cue? 

And can I then disable this fader from doing any manual timing overriding for the few cues that don't have manual times in them? So that if an operator makes an error and drops the fader, cues without manual timing data still fire as programmed?

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