1. This museum teaches both Brazilian Jiu Jitsu and Kendo. I don't know if he has formal qualifications, because of technical and historical problems, they are not popular in China, and I have never seen a Taoist museum teach them together. I suggest you study whether he has teaching qualifications or something before you go.

2. You are over 20 years old, so it is not recommended that you practice these martial arts with high technical content, because Brazilian Jiu Jitsu has high requirements on health and other aspects. If you don't intend to concentrate on practicing, it will be difficult to achieve something, which is not as popular as Sanda and Taekwondo.

The rest depends on your personal hobbies. You don't have to learn these things. If you want to practice fighting, you can go to the gym or the gym, where there are generally corresponding training courses.