2. I think you're having a false idea about how groups are created.
They are similar to events in the event sheet, so pressing "g" creates a new group and then you have to drag/drop events to make them sub events of the group.
Selecting the events prior to pressing g is not supposed to "group" them automatically.
The fact of selecting events is there just to "position" the group in the event sheet on creation of it.
It is indeed true that if you select a comment (the appropriate name of "notes" is comment) and press "g" then no group is created.
Might be indeed a bit of a bug/unexpected behavior in the editor.
But once again, selecting several events at once is no use in the creation of the group.