I can not understand :" trading fidgeting babies","solemn-faced boys" and " in the cosy confines."?

While everyone waited fort he ceremony to begin – giving sideways hellos and trading fidgeting babies – my eyes scanned the white nuptial carpet from the candlelit altar all the way back to the double doors, which usually opened out into the stained city street, but had just been shut by two solemn-faced boys. That´s where they would make their entrance, I thought, as I surveyed the back of the church. None of the wedding party were gathered in the back like I suspected they might be, only the altar boys who were now coming forward along the aisle dividing the bride´s and groom´s families – a prelude to the choir – whose presence made me feel secure in the cosy confines.