1) On the listbox's Double Click event put something like:
DoCmd.OpenForm "frmMyForm", , , "criteria expression here"
where the criteria expression is any valid criteria, e.g. "[Name] = '" & Me.txtName & "'"
2) In the listbox's properties, set the Column Count property to 2, set the Column widths to e.g. 2";2" (two inches each), set the list width to the sum of the columns (in this case 4"), and set the Bound Column to 1 or 2 depending on which field you want to use in your calculations/operations.
On your listbox's recordsource property, make sure you're selecting the two fields in question. They'll both show up on your list but only the bound one will affect anything.
Michigan Dept. of Environmental Quality, Air Quality Division