Legal Question in Wills and Trusts in California

As long as you are getting your fair share, and not more than that, there isn't a potential undue influence case against you. You can be the trustee, although typically your mother would be trustee and you (or you and your brother) would be successor trustee(s).

Keep in mind that if you are the initial trustee of the trust, then you need to keep extremely good records and avoid any cash transactions because you can be made to account for every penny of every transaction you conduct as trustee.

As to your last question, you probably won't find an answer here. Trust and estates attorneys don't use the self-help forms that are published online. Also, in my experience, there's a very good chance that you'll make mistakes - the best advice I can give you here is for your mother to hire a trusts and estates attorney to prepare the trust.