It's poorly written in places and incomplete by my reckoning. Making a complex subject accessible isn't the easiest of writing tasks, and if you don't manage that, you scare customers off instead. The conversion process is correct, though it ignores the choice of rendering intent and gives you nothing on soft proofing. Monitor calibration doesn't always address luminance/brightness; you need software that walks you through that. "RGB colour space" in this instance equals "Adobe RGB" (not an error that someone knowledgeable on the subject would usually make). You'd be better off brushing up on technique elsewhere and then just exploiting what is a rare service in the UK, provided it sorts out the apparent problems with file delivery. There's some good stuff on the Internet by Jeff Schewe, Andrew Rodney, Julieanne Kost, etc, etc.