trimming controls

I'd like to have fine control over trimming, so that I can save portions of a movie. Ideally, I'd like controls to allow me: (1) to display the first frame in a segment; (2) the last frame; (3) play the selected segment from start to finish - both at normal speed, and slowly, frame by frame, with speed control; (4) to show the segment with and without cropping (i.e. to show the segment uncropped, or alternatively with cropping applied) - once again, with speed controls to allow full speed or at various levels of slowness.