Certain compounds are harder than others, they all work, just some work faster. Here's a link to a post that explains it a little better. my-sharpening-compounds-reference-t6133.html
As far as the nano cloth, yes you would need a different piece for different compounds.
As far as which strop to get, I would recommend marks strop kit, it comes with one micron paste you use on the balsa wood, followed by Bare horse leather, I use this progression all the time after the Rika and it works great.http://www.chefknivestogo.com/haamstkit.html