Most of your interview questions are too unspecific to give really good answers here, so here are only a few short thoughts.
Q1: basically everything that can't be done easily in PowerCenter regarding file handling. For example, creating a file list. Or renaming / moving some files before / after processing.
Q2: too unspecific. I don't really know what you want to know here.
Q3: In Informatica? Not at all. Compressing files is a job for command-line tools.
Q4: depends on the task to be done. Pretty common ones are ls, rm, cp, tar, mv.
Q5: see Q4.
I suggest you go through Youtube videos by TekClasses. The link to the same is provided below :
Go through the different videos available in this channel on Informatica. It has answers to most of your questions.