Regarding ziyarat ashura, do you think it’s a good idea if I do the 100 salams & Lanats on the way to work (as I don’t have anything meaningful to do during that time) and can therefore use the extra free time at home for other good deeds? Or would there be more reward in just doing everything in one sitting?

Yes sure you can do that, or listen to lectures, Quran or Duas also beneficial