My scanner is the SDIII, not the IV, but the differences aren't all that huge. The Minolta software has an OK cropping facility (adjust the dotted frame in the prescan) and there's no reason to scan parts of the frame you are certain you will never use.
Saving the highlights is trickier, because the Minolta software is fairly crude. The SDIII software has a series of tabs available in the 'prescan' mode that let you make some adjustments. The tabs are arranged so that the workflow goes from left to right. Very easy to make the corrections once you get the hang of it.
Lately I've been scanning BW neg films as BW neg with 1x sampling and getting acceptable results but it's very dependent on the quality of the original negs -- and most commercial processors doing conventional BW seem to overdevelop.
The clipping comment is intriguing. I see this with a couple older film types and some images, but not across the board.