I'm not your nine-to-five-type of person.

@1:

Das kann man m.E. aber auch ganz anders verstehen - etwa im Sinne von "ein typischer Acht-Stunden-Job ist nichts für mich" ...

nine-to-five-type of person
ein typischer Acht-Stunden-Job

they could be interpreted to mean the same IMO; i.e. regular working hours are not so important, I'm flexible, prepared to work sometimes in the evenings, at weekends etc. But the OP means I'm prepared to work overtime if necessary, I think - a somewhat narrower definition...?

I disagree with #1 and #2.

The OP means that he is not someone who drops whatever he is doing and rushes out as soon as the shift is over (like Fred Flintstone, or Homer Simpson).

This does not mean that he does not like regular job. Maybe he enjoys it a lot.

He implies, however, that he has a sense of duty and accomplishment and sees his job as more than just a chore.

"I am not someone who drops everything as soon as his shift ends", or "I don't drop everything as soon as the bell tolls."