In the US there are definately no loop belts for infants. The child under two is held on the passenger lap with the seat belt around the adult passenger only. If a seat is purchased for the infant than a DOT approved cabin seat provided by the passenger is acceptable.
As far as life vests, in the US the major airlines have child vests. Some airlines use adult vests for the child. It all depends on the type of life vest. The dual cylinder two chamber vest with the back flap is easy to place on a child. There are also infand pods on certain airlines.