Doubtful Foods

4 questions

Is it obligatory to avoid foods whose ingredient symbols are said to be derived from pork, and is it obligatory to disseminate this warning?
What is the ruling on consuming foods containing gelatin, monoglycerides, diglycerides, pepsin, and rennet?
Is it permissible to consume a carton of powdered milk if, after consuming part of it, the buyer learns that one of its ingredients, lecithin, may be derived from pork, or must it be disposed of?
Is it permissible to marry a woman who grew up in a Christian household and attends church, but then became doubtful of Christian beliefs (especially the crucifixion and redemption) and believes in the existence of a Creator for the universe, though not in the current Christian understanding?