Thank you for your remarks!
Question 1: Yes, 'disc' = 's2' in the plot (I have to fix this). This means "discrepancy". A high discrepancy means that there are a lot of variations accross the sequences. The range of the discrepancy is [0, maximum possible distance] and there is thus no threashold values. But you can compare some values.
The Levene test (which seems to be non-significant in your case, see the image) test the significativity of the difference in discrepancies. This test can be run with the dissassoc
function. In the tree, the Levene test the equality of discrepancy in the terminal nodes (again, here differencies seems non significant).
Question 2: In the printed output, the sequence in square brackets [] is the centroid. This is the most central sequence of the subgroup.
Question 3: see answer to question 1.
Hope this helps.