Hi,
1. You can enable/disabled triggers under the General Options -> Logic & Behavior panel. You are looking for this option exactly: https://i.imgur.com/4EWcq9S.png
2. Yes, that is possible, by changing the checkbox logic here: https://i.imgur.com/I5u2wnl.png
I suggest experimenting with the different values.
3. Those could be results that does not have relation to the given taxonomy, you can change this option to exclude them: https://i.imgur.com/hoob1li.png
