Hi - congratulations on your baby
I don't have personal experience, so can only give you general information.

Between 1 month and 6 months of age, the exclusively breastfed baby will take anywhere from 500-1300ml per day but the average is 800ml or thereabouts, and that's where most mums aim for to begin with. The amount of milk babies take at any one feed will vary enormously - 800ml/day with 8 feeds per day doesn't mean they always take 100ml per feed, for eg.
When taking a bottle, babies will sometimes take more than they need as the teats allow milk to flow quite freely and it may be more difficult for them to regulate, so they just keep drinking even after they're full. You can try pacing feeds to see if that makes a difference, or it just may be that he needs more than average.
The amount of time you pump depends on how it works for you. I would suggest pumping till the flow slows significantly, then stop. Many mothers find that more frequent, shorter pumping sessions work better than less frequent, longer ones.

To get more specific information that's helpful to you, it might be useful to understand why you are pumping, if you don't mind giving more details.