Listbox Column Widths and Lengths -Autofit?

Please forgive me if this post shows up twice; my first attempt disappeared on me (the system logged me out when I tried to submit it).

I've got a Listbox in a User form that looks at data on another spreadsheet purely for informational purposes, not to be selected. I have two problems with what it's doing:

1) There are 23 columns, of varying widths. However the listbox uses a standard width, so some items are truncated and some have too much room.

2) The data changes, and the number of rows may change from 2 to 15000. I've set the RowSource to cover the ranged from A1:W15000, but if only 2-300 lines are selected the user can't grab the scrollbar button to scroll through, but must instead use the arrow, which is rather slow.

Is there any way to set the column widths to match the data, and the Range to only go as far as the last populated row?

Thanks in advance for your help on this.