A: Yes, this can be used on a standard 1" shower head.
A: Yes, the extensions can be removed.
A: There are knobs on the back that you turn. You can slide the shelves up or down and then tighten the knob.
A: there is knob on the back of the rail that is used to loosen and tighten the rails/shelves. once loose they are free to move, also the entire rail is length adjustable (telescopic).
A: no adjusting for me.
A: I didn't. It was usable right out of the box.
A: Just simple rotating buttons that tighten/loosen. You can move the shelves up and down, and also remove them completely if you want to swap their location.
A: Dials on the back to adjust the shelves.
A: no adjustments.
A: You can adjust the shelves by moving them up and down.
A: They slide up or down the center bar and lock into position.
A: Yes, this unit is rust-proof.
A: I don't know. I've gotten shower items before and after about a year the rust began to appear.
A: Looks like it. The wire parts are stainless steel and the body is aluminum with bits of plastic.
A: The manufacturer states it is. I've had mine in action for 2-weeks. Time will tell.
A: Hello NFV, All of our shower caddies are rustproof and are backed by our excellent 5-year warranty. Warm regards, simplehuman