Hi,

Mothers and babies are designed to sleep together and research (Helen Ball, James McKenna etc) demonstrates that mothers get the most sleep when they sleep with their baby. These researchers have studied many mother/father/baby groupings and find that babies feed more frequently during the night, and that the mothers report getting more sleep/feeling less tired than mothers who don't sleep with their baby. Mothers keep their babies safe in bed by adopting an instinctive position in bed (now - don't think tooo much about it - it's instictive!) But basically the baby is sleeping facing the mother, often with mother's arm underneath the baby and her legs are curled up below the baby which stops him slipping down the bed.
Leaking is often a safety valve mechanism - we leak when we are too full. Because babies usually feed more during the night, your breasts are kept well drained and are less likely to leak. But I can tell you from personal experience you can sleep through anything if you are tired enough - spew leaking breastmilk - anything. We had a fabric mattress protector on our bed - and a towel on hand to place over anything that came out. Sleep topless or in an open pyjama top - part of the deal is you want to be disturbed as little as possible. No bras necessary. Your baby will learn to self attach.
Like anything new, it can take a little time to get used to a new body in the bed, but stick with it. Sleeping with your baby is one of the sweetest gifts we are given as mothers. (and they grow up and move out very quickly)