Irrelevant. If the quotes are sourced, they're valid. Just because they're a Christian activist site doesn't mean the founders didn't say those things. Just because HomerJS may be hostile to Christians doesn't mean the founding fathers didn't say what he quoted them as saying.
Not irrelevant at ALL. Activist sites will often choose quotes selectively and leave out other pertinent information. From the link you provided I would get the impression that most founding fathers were Christians when they were not.
I was just looking at that book the other day, though I haven't read it to the end. What's important to me is that they appeared to care for the practical aspects of Christianity, which would certainly inform their approach to forming a new country.
Would you consider someone who rejects the divinity of Jesus to be a Christian? I wouldn't. While I'm not sure what you consider to be the practical aspects of Christianity, the basic principles of Christianity are shared by a lot of religions, it's not particularly special in that way.
I don't know man. That's the impression I get. There are more than one on this board who talk about a Christian Sharia like it's an actual possibility.
You see people on this board who claim that Christians are about to violently overthrow the government and create a theocracy? Who are these people?
What I see is people (rightly) complaining about Christians attempting to enforce their religious dogma on others, which is a perfectly valid complaint considering how often it happens. Again, a fairly large subset of Christians want our government to pay people to engage in compulsory education of children with Christianity's creation myth. That's pretty fucked up.