Hi Andy,
There is no such setting at LISTCUBE(BW 7.3) level, i tried a lot to find out at listcube screen. There is no chance to see descriptions. But if you select particular record, choose details ,then we can see descriptions otherwise nope.
About extending columns, i think you need to do manually if output displayed in alv grid list.
select all(Ctrl+A), click on two columns joint, it may adjust as per the length(guess).
Thanks