OK, I had a similar setup to you - but with only one blog and static HTML pages around it.
I thought it would be great to convert it to use WordPress as a CMS (content management system) and supply all the "static" pages as well.
So I spent a LOT of time changing it so that my wordpress runs as a CMS.
To be honest, I'm not sure it was a great thing to do! I still have issues to fix, and because my install is no longer standard, it seems to throw up some interesting little quirks and bugs. If what you have ain't broke, then don't fix it!
Since WP2.0, you now have a option of a "static" front page, so things have got a heck of a lot easier to make WP do this for you.
What you want to read:
(but its never that simple!)
The answer to the 2nd paragraph is yes. but I'd recommend
I did it, it works, but it just adds an extra and unnecessary level of confusion, and again is not this simple!
You'll find most of the following stuff hugely out of date for WP CMS stuff now as it was mostly written for 1.5:
but its worth reading around a bit.
And if you want more info, then reply and I'll help where I can, but I will say that there are few more complications that any of the guides I found made out.
Also try search on "wordpress as a cms".