Serving as Trustee of a US trust?

While this subreddit has had many posts about becoming a beneficiary of a US trust, I may be in a position to become both a beneficiary and a trustee, and I wonder if that creates any specific issues for me?

Yes I'm going to pay for professional advice, but before doing so, appreciate any comments; below are specific questions in bold.

My mother, brother, and I plan to set up the following (I am long-term resident here, the others live in the US and have no Japan connection):

1. Amend her will to create a revocable trust, which will become irrevocable upon her death.
2. All her assets will get moved into that trust while she is alive, so her estate can avoid probate
3. As long as she lives, my mother and I would be the trustees.
4. When she dies, the following benefits will be paid out:
   1. my brother will become a beneficiary with ongoing benefits. (he has some health issues, but an SNT doesn't seem to fit his needs).
   2. I would be named as a beneficiary to receive a one-time inheritance, which I suppose will be taxed in Japan like any normal inheritance, ie the existence of the trust would be irrelevant? (statutory heirs being 2, my brother and me)
5. After my mother pases away, another relative (a cousin of mine) might become a trustee. I would also very likely bring on an institutional trustee to professionalize it, for a total of 2-3 trustees. I would receive some payment for trustee services. Will Japan tax this just like any earned income? Does my role as trustee create any exposure? (eg, if NTA deemed I had some discretion to use trust assets for my own benefit)?
6. In the future, if my brother dies before me, the balance in trust would be paid out to me. If I'm living in Japan in that case, I suppose this would again be taxable like a normal inheritance? (with me now as the lone statutory heir)