Re: breastmilk bottle
By 7 weeks, you should be fine to introduce a bottle. This link covers bottle-feeding a breastfed baby: http://kellymom.com/bf/pumping/bottle-feeding.html
Babies can develop a preference for the bottle at any time during their nursing career, so always be watchful. If you feel like your baby is developing a preference, try to put the bottles back on the shelf for a while.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"