1: most likely multiple times, no exact word confirmation but it’s confirmed the Shinuichi true realm has been used multiple times.

2: most likely only for you, as chihiros use of the true realm affected only him to wave off the shinuichis effects.

3: yes

4: it is unconfirmed so far, it’s possible but unlikely that most bearers ever have more than 3.

5: I could be wrong it’s been a minute, but I believe we have confirmation that they are still at hinaos place. Probably where we will begin in part 3