Firstly I never used any of this on my working sheepdog, I do this with my other dogs..
I train an emergency stop, basically it's a command to stop the dogs dead in their tracks, it's worked on every dog I've trained except my lurcher George, and I haven't given up on him, what I do is, and I try to do this every day at first, throw a treat over the dog to get some distance from me, then wait till the dog turns to return, as its coming back I throw another treat over their head with my throwing arm ending in a stop signal and say, or shout, depending on distance 'stop', later in the process I do this with the recal command when we are out, I use high value treats for this (roast chicken, not whole ones just pieces)
I've got an acme sheepdog whistle, can't whistle with my fingers, I know with my started sheepdog when I got him I had to learn the whistle tones he'd been started on, I was ok at it but not reliable enough, as we only ever worked in smallish fields I reeled on voice commands, they have incredibly acute hearing
As for training the hoops on poles it was just a ase of breaking it down, first taught the touch command, so the dog touches an object on command, then introduced the biggest ring which I called red, then taught touch, fetch and drop, then, and this takes ages, taught touch whilst holding red on the pole and he eventually worked out to put red on the pole, I then combined all this to the command red, so he'd put red on th e pole as one action, I then did this withe next ring etc, and then did red, blue, green, and viola, if I recall correctly took me about 6 months with a 4yr old dog