My answers to the questions are as follows:

INTRO

  1. Finds “cat” in cat and “hat” in that, chat and phat.
  2. Finds all four numbers.
  3. Finds 501-1234 and 234 1252.
  4. Finds both “run” and “runs”.
  5. Finds all numbers starting with 1.
  6. ar?t: at, art; a[fr]?t: at, art, aft; ar*t: at, art, arrrrt; ar+t: art, arrrrt; a.*t: all

PART I

  1. \b(eat[sei]?[nr]?[gy]?|ate)\b
  2. \b((M[uao’]+mm?[ae]r?) ([aAeE][lI][- ])?([GKQ][h]?[au][dthz’]+[aā]f+[iīy]))\b`
  3. \b([IEHieh]i?[sṣ][bfp][aā]h[aā]n)\b

PART II

  1. In Sublime Text: FIND (\w+), (\w+)$ REPLACE \2 \1
  2. Connect all cities in the list with pipes (“ ”).
  3. \b([\w ]+) \(Lower Austria\) \b([\w ]+) \(Salzburg\)