OK, brief answers:
"Before holding this guy up as the spokesperson for all right-thinking rational people"
I don't.
"a) read his tome with the same critical attention as you'd give a religious text"
He positively invites that. He is a scientist - he like people to offer evidence to refute theories. That's all part of the job.
"b) question whether his approach is based on the sound scientific principles he purports to hold so dear"
What's the evidence that it isn't?
"c) question whether his understanding of his 'target' (for want of a better word) - in this case Christianity, mainly ?is sufficient for him to tackle it directly"
I suppose this is the criticism which is levelled at him the most often - he is a scientist, not a theologian, so what right has he to write a book about the God issue? Well, he is a critical thinker and a rationalist. He does, again, address the issue himself - he only pokes his nose in because religion pokes its nose into science first. They are both exploring the same ground - what the world is and where it came from - so where's the problem?
"d) look in to the view of those who openly disagree with him - I'd recommend Alistair McGrath - who happens to be (unlike Dawkins) highly qualified in both science and theology."
He's already posted a response to McGrath on his website, I believe. I've not read McGrath, but the responses I have read lead me to believe that he merely re-states the ideas Dawkins has already tackled.
"As an example I'd also point out that Darwinian Evolution is, at present, a 'theory' that people choose to believe (I do, FWIW). It has a great deal of merit and some evidence to back it up, but is by no mean possible to 'prove' this theory beyond all doubt."
It's the current prevailing theory for which there is the most overwhelming evidence. It has a consensus in the scientific community. Anyone wishing to posit an alternative theory is welcome to do so, as long as they back it up with comparably rigorous and extensive evidence, analysis and published data.
"Most people of faith would feel similarly about their chosen religion, I think you'll find. They've looked at the evidence, and made a decision that this is the best explanation for things avavilable at present."
But there is zero evidence for the existence of God.
It's like the Loch Ness Monster. There's pretty strong evidence that nothing is there (600 sonar sweeps done by the BBC a few years ago) and some evidence that something is (a few blurred photos and anecdotes). There are theories on both sides, but the weight of the evidence is strongly tipped one way.