gelatin/bishul akum

Question

I was wondering if you could clarify your position on the permissibility of gelatin. It seems that Rav Moshe Fienstien prohibits gelatin from non-kosher animals.{Iggros Moshe, Yoreh Daeh 2:27} Also,in your Halacha section related to bishul akum you wrote, "if there are combinations of ingredients and some would be ok while some would be a problem we go after the main item.When you say main item, do you mean in terms of majority or just in terms of which item you desire more? Thank you, Benjie