Travel, Language School and possible relocation

Hello,

I hope, this is the right subreddit, to post this, since the other related subreddits specifically don't allow tourist/non-resident posts.

I'm currently looking to go to a language school in summer, in Tokyo. I intend to stay for at least 6 months and actively go to school and learn the language.

Since it would be my first trip to Japan I want to see the country first and go to school afterwards.
So, ~3 weeks of holydays and travel.

I'm from Switzerland, so I can stay in de country for 90 days without a visa.
Obviously I will apply for a student visa, before i fly to Japan. I suppose, the student visa needs to start, when I also start school.

Now to my questions:
– Am I correct, to assume, I can just travel Japan first and start school with the appropriate visa, without any issues?
– If my research is correct, I can work part-time, just with a student-visa. Is that true?
– If I like it in Japan and can (by some miracle) manage to land a job in Japan, can I "just" apply for another visa within the country or do I need to leave it, in order to do so?

Thanks 🙂