Hello Rolls. The black tool kit was for the 2nd generation as I remember it. The darker set on the first cleaners was dark brown, though in that brochure there it does of course look black. Because Hoover discontinued the beige and the brown tool kits to make way for black, I thought the beige Powerglide with brown tools may have been the first version, though of course both cleaners in the Powerglide range were very short lived and were built on the cusp of many changes Hoover were making, so I agree with you that the red model could have been first.
Although I am certain the long-necked floor tool was designed for those cleaners with the remote control cleaners with very short hose handles, it does seem that Hoover supplied it with other long handled cleaners too, based on my memory of the Powerglide I saw, and the booklet above, and the cleaner ryry owns. Knowing Hoover, they probably did this to use up stock of existing parts in an existing colour.