His letter pretty much ignores the possibility of faith based belief - that would be due to the fact he does not have faith in such things himself. Faith in anything supernatural is beyond science to prove/disprove so to turn around and ask the question "show me the evidence" for "everything" is a failure to recognize that Faith in God, Faith in life after death or Faith in any kind of supernatural life etc, is beyond science and may not have direct physical evidence.
Nothing in the universe is "beyond science," therefore everything in the universe must have some scientific evidence for it. If no scientific evidence can exist for something, then it is beyond our universe and completely irrelevant to our lives.
Personally if I am going to write a letter to my daughter when she is 10, I think that of all the htings I would writer about or give advice to her about, critical thinking would not be high in the list,
I like and respect you, PSac, but please don't procreate if you don't plan to teach your kid critical thinking as one of the most important skills she will ever obtain. There are enough morons in the world already.
The things you list to tell your daughter are things a good father communicates with his children in personon a regular daily basis and therefore would have no need to preserve for posterity in a formally written document. I hope if you do have children that you will both tell them the things you mention in your post AND teach them critical thinking skills. Those skills will serve her/him well and work both ways.
Here's my experience with the Dawkins letter: I printed out this letter and read it together with my daughter at age 10. She's smart but got bored well before halfway through it. So I paraphrased and just discussed the points with her. It is a very good and relatively simple treatise on the subject of credulity and critical thinking but seems to have been written more for the book it was published in than for an actual child.
As for the ad hominem attacks on Dawkins by his religious opponents I wish I could say I'm surprised but I've come to expect such behavior of Christians unfortunately.