I just got into polishing a week or so ago. The tripoli and white rouge tearing the cotton buffs up is evidently normal, and will stop. I tried heating the tripoli with a lighter for about ten seconds, not long enough for it to melt, just long enough for it to get warm(it was cold as dirt the day I started). I found that you have to use some force with the buff(bear down on it)so it will pick up the tripoli or rouge. I also learned not to put to much tripoli on(it will gum up and stick to what you are polishing).
I had some decent success with it, but the TC valve cover I was polishing was a really bad casting. So I just went back and hit it all over with the 180 grit poly wheel for a satin hi-tec finish(like the one 140 has on his car). I think it will go better with what I have planned.
Hope you have good success with your project!