Your notation is wrong because fd01:976a:c200:6f1b:0:0:1::2/127, after specifying 8 groups you are trying to specify with (::) notation before last group 2. If you try the same with fd01:976a:c200:6f1b:0:0:1:2/127 notation without :: it will work.
We will use VIM-2x card for stacking when we have 1G switch for stacking. You can do show stacking-support to see which ports can be used for stacking.
Q1: if you didn't use any address-based option (or) "address-based lacp" without specifying any algorithm like L3, L3_L4 and custom then default L2 algorithm will get set. So both CLI would result in no difference.
Q2: "show port sharing" command yo...
