Not a bad idea.
So let's look at a screenshot:
So I show the clip size when you select a clip (total number of bytes), and you can add a column for the clip size in the grid if you choose.
It wouldn't be hard for me to add a LINE COUNT to that bottom row when you select a clip.
It would be a little more inconvenient for me to add line count to the grid columns, but it could be done going forward for new clips.
Now as for adding "selected lines" that is a little messier, so im not sure about that. But maybe.