questions about BF cf to FF

[WobblyPig]

This has probably been asked time and time again but re: advantages of BF cf to FF - is it that formula is actively harmful or that breastmilk is actively protective.
Is the risk graded i.e. risks increase as the amount of FF increases? If so how much could you get ' away with' without increasing health risks? Is there a threshold level of formula exposure or lack of BF ? If so is this different for all the health issues E.G. eczema cf obesity or IQ?

Sorry to fire off so many questions.

I am not sure when I should get concerned about the vomiting if I ignore the weight. Should I stop getting her weighed or continue ? When should I be concerned about weight gain ?

I was advised to weigh DS every week for first 3 months or so and then every 2 weeks to keep an eye on his weight. I just go every couple of months now at 10 months.