How old is your baby?
The length of time on a nursing session is individual to the baby and also depends on their age. Some are more efficient and quick than others. In the early days my LO took about 45 minutes to feed. Now it's about 5 minutes.
Unless you're having supply issues there's no need to pump after every feed. Plus if it's early days pumping too much can lead to an oversupply.
It really depends on what you're aiming for as to how often you pump. I am away from my LO one morning a week and I pump maybe every two days or so, once in the morning after his first feed. If you envisage being away more frequently you'll need to pump more often. How long to pump also depends on the person. I don't respond amazingly well to a pump and it takes me about half an hour to get 2-3oz, but some women can get a lot more. I just stop when the boobs have given up lol.