Ok, I will cover the "Short" run issue..
When you first start an engine, COLD, clearances inside the combustion chamber (Cylinder(s) are often a bit different than when at operating temps.. Some fuel may sneak past the rings and mix with the oil, also acids can get into the oil, acids that normally can't take the heat so they get out of the frypan (oil pan).
So constant and frequent short runs damages the oil and may even eat a hole in the bottom of the well (oil pan) Have seen that happen on ONE engine.. Just one, a car.
That is why the 30 minutes at half load bit.. 30 Minutes gets it up to OPERATING temps, which is hot enough that moisture, acid, and fuel residue in the oil get boiled off and go by by never to bother you ever again.
So, yes you can do a short run,, But try to give it a workout if you can If you frequently do short runs make that full half hour, or better yet a full hour, more frequently Every 1-2 weeks I'd recommend.