#1: are you certain that there’s difference in passthrough quality between recent fw versions? The only things changed that could affect that are some Infoframe parameters. Did you try if “HDMI ITC” option makes any difference?
#2-3: these seem to be resolved now.
#4: You need to use you TV to switch to 4:3 aspect 480p. Both 16:9 and 4:3 480p use 720×480 resolution, but the latter is non-anamorphic format and needs to be handled differently by the display.