Eating In: Ameda

Questions About Breast Pumps

I have a lot of questions about breat pumps. I will have to return to work about 6 weeks after having my baby so I will need to pump my breastmilk. I have heard that the Medela and Ameda pumps are good. Also heard that the Lasinoh is comparible to the Ameda. Any thoughts? Do most pumps come in standard sizes so any bottle can attach to it? Also anybody know how often I will need to pump? Obviously, there's a lot I don't know about pumping!