Hello Joern from Bavaria.
A person is pregnant for nine months, more or less. There is a progressive sense, even though we don't say "while she was being pregnant."
1. When my wife was pregnant, I landed a job at Harrods. -- At some point during her pregnancy, I got the job.
The problem with A is that it could mean that the person worked there only while she was pregnant. Although "landed" should be a momentary thing (he got the job), someone could read it as meaning that the duration of the job coincided with the pregnancy.
B is completely wrong.
2A - yes.
2B - no
3B - no
Student or Learner