The base of the nipple should encourage the baby's lips to flange outward. Many mothers in my practice have found that the Avent bottles and nipples work very well for their breastfed babies. The answer to this question depends upon how old your baby is at the time you return to work and how often your baby has been nursing during the period of time that you will be away. You can expect to pump every 3 hours that you are away from your baby. If your baby is older than 6 months, you can adjust your pumping schedule accordingly, being careful not to let yourself get uncomfortably full and run the risk of a plugged duct.
Women use many different containers for freezing their milk.
You can use a glass or plastic storage container, baby bottle, or plastic breastmilk storage bag. Breastmilk freezer bags are made of a thick polyethylene to prevent contamination of milk from punctures or splitting. Leave some room at the top of the bag to allow for expansion in the freezer. Always label your expressed milk with the date before freezing. It will keep in a deep freezer for 6 months or longer, provided that the freezer stays at a constant 0 degrees.