you can find out what you need to know about salt by reading this book
If he is found to be illegitimate, i.e. from Kenya, then everything he did would be illegal. That will cause an enormous constitutional crises because we have not been here before.
This might be interesting for you. Its over 3 hours, and the presenter is a little quirky, but the info is good. I have watched 2 or 3 times in the last few years, and I hardly never watch youtube vids.