How to properly adjust rim brakes for a touring bike?
Touring bikes, as you said, carry way more weight.  Beacuse of this additional weight they are prone to brake squeal and you need to pay closer attention to your wheels for loose spokes and out of alignment rims.
Make sure you have good spoke tension that is even all around the wheel and that the wheel is true.
The only major difference in brake setup from any other brake setup is just to nose in your pads more so than you would usually for an unloaded bike if it's needed.  It all depends on how flexible the brake mounts/arms are on your bike.
My Surly Long Haul Trucker doesn't need any nose in when unloaded but when I have an addition of a trailer and fully loaded touring bags the brakes howl when going down hill so I nose them in and the howl goes away.