I recently found out that a lot of food ingredients can be derived from pork, for example food colouring, which is in everything, etc... These ingredients are in almost all food and drink products, even in medicine. I try to do my part and call the companies and ask them the source of their ingredients, but I can't call every one. My question is if I don't know that the ingredient is 100% from pork, but there is a chance it can be, should I avoid it, or say bismillah and eat, like my friends tell me to do?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

May Allah bless you for your serious wish to follow Islam. You are not required to search with minuteness for the ingredients of food, i.e. it is sufficient to depend on what is strongly believed in such cases. In other words, it is sufficient for a Muslim to do what he can do to know the ingredients of the food and seek help through what is written on the label. If you doubt, it is safer to avoid using or eating this and that food. But, if you make sure or strongly believes that there is something Haram in the ingredients, it becomes strictly Haram to use or eat such food.
Allah knows best.