What constitutes valid evidence?
Whatever you want it to be.
There is no objective definition of "evidence", and I don't think there could be. Evidence is that which persuades you, and there is something unavoidably subjective about that.
Science wants evidence that is repeatable and is consented to by the scientific community. So scientific evidence is not what persuades you, but what persuades you and the consensus of the scientific community. And that has generally worked well for science.
Must Faith have evidence?
Presumably. But it is more of a personal thing. Roughly, faith evidence is evidence of the trustworthiness of whoever is making the assertions that you take on faith. So
Faith (the evc member) gave a higher trustworthiness to the Bible than I ever did. Back when I was an active Christian, I did trust the Bible, but only to the extent that it was consistent with experience and with what I knew from science. By contrast,
Faith gives it the highest trustworthiness, even if it seems to contradict experience and science.
Should people of faith be allowed to get angry when their beliefs are challenged?
There are times when people cannot help but get angry, so I don't think "allowed" is involved.
How should creationists defend their faith and still represent science?
They probably cannot do that.
Fundamentalism - the anti-American, anti-Christian branch of American Christianity