Rbb,
In your quest to learn about Robots, you'll probably find it very uncommon for robot manufacturers to give away any of their literature. Mainly, manuals and literature that you probably need are usually not readily available on the Internet. Even if you do buy their particular brand of robot, you'll still probably find it hard for them to give up any advanced literature. They obviously make money off you when they sell the robot to you, but they also want to have a continued relationship with you and your company. This is where the "you needing them, more than they need you" aspect comes in. Parts and technical support are big money makers for robot companies. You'll find this out if you ever need them to come and fix one of those robots.
My suggestion is for you to talk to and become close to someone inside the robot manufacturing company. Build good relationships with them and you'll start getting the manuals that say "confidential". This is the literature your after, but don't expect them to give you anything without you giving them something in return. I understand your frustration that there isn't anywhere to turn to on the Internet that has useful information on IDUSTRIAL ROBOTS. I think it’s only a matter of time before someone puts up a message board or something to start exchanging some helpful information on robotics.
Good Luck,
Tim