Hi, I'm currently doing an Occ psych masters so hopefully I can help.
1. You don't need a doctorate to become an Occupational psychologist, though by doing either a professional doctorate or PHD you would qualify for chartership without having to do the supervised practice.
2. Stage 2 also involves completing a log book and experiencing several areas of occupational psychology practice, this has to be approved by the BPS. Once it has been you become a chartered occ psychologist. But you can work in occupational psychology without being chartered
I have a few useful presentations on chartership if you want any more information on it.
I've enjoyed the masters, there's a lot of areas to cover so there's a lot of diverse areas to work in as a result. I would recommend trying to get some relevant work experience before you start so that the course content makes sense. If you want to know anything else let me know