Nightmare - hehe - the name of a difficulty setting in Doom

I broadely agree with your ideas, Black Elk.
The encumberance thing brings back fond memories of my trips between Beregost and Wyrm's Crossing, shuttling Ankheg carapaces, with the overencumbered party mincing their way across the forest like pencilskirted geishas ...
Scroll/elixir/spell duration and summon times - all "until Long Rest" should be eliminated and cut down to 10 rounds. A few I suppose could stay at 100 rounds.