It really depends on your horse's stride and what you want the poles to achieve.
For your horse(s) to start (I see you have a TB and a Paint) I would start by placing the poles one bigish step apart (almost as far as you can possibly step)and then play with them and find out what is right for your horses' normal stride. As your horses' get used to the poles you can start to adjust putting them too wide or too narrow to lengthen and shorten the stride.
For the canter, usually if you put the poles 2x as wide as you do for the trot it is good. Make sure your horses are used to 2-4 trot poles and single canter poles before you start even 2 canter poles in a row.
Depends on the horse and the exercise. I take 3 foot steps. So for a series of trot rails I generally space them out about 4 feet, which is one step and drop the rail a little in front. For a series of canter rails I space them out 9 feet apart so that's 3 steps.