How long?

FTM here exclusively breastfeeding my 6week old. How many minutes do u mamas nurse ur babies for at a time? Do u offer only one breast for each feed and give the other breast for the next ? What's the normal time (minutes) a baby feeds for? (Question to the breastfeeding mamas out there as bottle feeding time is obviously different)

Also how long without feed can I let my baby sleep for if she doesn't cry? She goes for 4+ hours in the night without waking up or crying for feed. Is that normal? Should I be waking her up to feed her ?