Hi Emma,
I started out with a very brief email enquiry, which I sent to two agencies, just to their 'general' email, but mentioning the agent I was interested in approaching. The email contained my writing career in a nutshell (it fits into one) and two or three sentences to sum up each of the three picture books I was proposing. Both agents invited me to send the mss.
I just sent Word documents (hard copies I mean), with the only guides being spread numbers (ie. 12 double spreads and one single). I didn't send illustration guides because I felt the text spoke for itself and I wanted to leave the rest to their imagination. However, the other school of thought says you should give a sentence or two on each spread to describe the illustrations. Actually, yet another school of thought says you should provide two documents: one just the straight text and one with the illustration guides on it. If he's used Powerpoint, is that because he's done the basic text layout with spaces for the illustrations? It sounds a bit 'advanced' in the first instance, but if the pictures are REALLY good, I don't see why not...the absolute worst thing he could do would be to send pictures that aren't completely brilliant. It's such a turn-off. My agent is sending out my picture books to publishers with no illustration guides, by the way - just text, split into spreads.
As for what else to include... Age range, definitely. It sounds rather broad and he may be better of narrowing the target. For example there are pre-school books for 3/4 year olds, and then there's a more involved pb aimed at 5-8 year olds (and then there's the really young stuff of course, which would be 0-3). It may well be that his series has a wider appeal, but it sounds a bit vague to say 3-7.
If it's a series with a main character, definitely include a punchy summary. Might be wise to show market awareness...ie. what gap in the market does his series fill... But as you say, full text for one book plus brief outlines of the others is right.
I don't have a Children's WAYB, I just use what's on the Net. The Booktrust site has a list of children's agents as I recall. I'll try to find it.
Umm, that's all the submission advice I can think of... The hard part is over to you!
Myrtle
<Added>http://www.booktrust.org.uk/factsheets/getpubchildren.html
The list at the bottom might come in handy.