Absolute 100% right on the speedbugs. It's quite some time that I flew the -400 and we were just changing to the new style EFIS when I left, but setting all the speeds from 0 just doesn't make sense. It's not only a matter of convenience but also of logic and safety. It shouldn't even be possible to set Vr below V1 and starting at 80 or 100kts for V1 would be enough.
I did not talk to DHC guys in person but I recall from talks with those of us who did that at least the test pilots did not care much about the "new style" EFIS (done only because SAS insisted on it we were told) and especially the speed bugs. Hearsay only, but when our technical pilot complained to a test pilot about the tedious speed bug setting he was told something like "ah, we just set them once a day and then leave them there"......
We landed power on but
AFAIK flaps 35 landings (instead of 15) are now used more often as they may be done with reduced prop RPM as well (which was initially limited to flaps 15 landings).
It's a pity that DHC didn't really take advantage of the cockpit technology available for the -400. Decent synoptic pages, an updated warning system and maybe even "dark cockpit" overhead panel would have made the 400 a much nicer plane.