1. You can add an <On Change> action to the input field, in which you will check the data enetered and act accordingly.
2. I don't think this can be done automatically. It seems you'll have to loop over the lines after the delete and update the number field of each row (e.g. using Get Index).
3. See the Tree4Notes sample application (in the Downloads tab of http://www.tersus.com/?Id=149).
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