This is great advice all around, but get a local lawyer involved to prepare your will. Even in US, there is not a single set of laws that apply to wills and power of attorney. It varies state by state. With a generic template pulled from the internet, you could just be doing a whole lot of work and ultimately be ending up with a document that has little legal basis. Do your loved ones a favor - hire a lawyer to do it…
If you don't, or cash strapped now, you can get by with Nolo press. If you can understand ROR, and programming, after reading their two books on wills and trusts, I think you can set up a trust and will, and skip the lawyer.
On the will get two signatures from people not in the will, and it does not need to be notarized in California. If you want to exclude a child out of a estate you must explicitly state that in the will.(Some kids got a lot of cash early on. Explain to them you love them. Make sure they are doing well, if you exclude them.) I recently did a will for a friend. Her daughter took all the family money when her father died--leaving her mother with nothing. The ironic part is her daughter is a multimillionaire in LA, with a successful business. She took advantatage of a bad situation, and a angry dying man. So yes, I didn't feel it was immoral to exclude her from the will of that friend.