Covering A Baby - How Much Is Too Much?

As a new mother, I spent hours searching because I never understood, nor agreed with the mentality that a baby should be bundled up in 5 to six layers of clothing to keep him warm. I find that most sources online insist that an extra layer of clothing is all a baby needs,and as for covering his head, that helps to keep the baby warm in cold weather but is a risk factor for SIDS. it's been a constant battle between me and my MIL as she insists that the baby be fully clothed, and wrapped in one or two thick blankets at all times even if she sweats. A change of her wet clothes is all that is needed. I was winning the battle till my baby caught her first cold ( from this same my MIL ) and now my MIL blames me even though I told her times without number that catching a cold has nothing to do with temperature and more with viruses and bacteria . We went to the hospital and the doctor gave my MIL more ammunitiom when he told her my baby's cold was a result of our failure to "cover her up " and advice's that we should always wrap her up completely. Especially her head.

My question is this

1. Is this doctor trying to overheat my baby?

2. Are his reccomendations correct?

3. Is catching a cold ( cough, catarrh, etc) really as a result of not keeping your baby warm?

4. Dressing a baby, how many layers is too much?

I'd like to get responses from health professionals because I want to know if I should find a new pediatrician for my baby.