At the moment, doing my dissertation, I'm in the lab from 9am to about 7pm every day. Too knackered to do anything once I'm home.
When we had lectures, we had probably 20 contact hours a week. But I'd say I did upwards of 40/50 including time spent writing things up, revising etc.
Very subjective as it depends how quickly you read and write essays for my subject. I'd say I average around 25; 5 on lectures, 3 on classes, 2 on tutes, 10 on reading, 5 on essay writing. But the reading and essay writing can easily increase to 25 total
In a week I have 12 hours of lectures and seminars. I then do anywhere from 5-10 hours of readings (depending how many assignments I have due the next month) and another 10-15 hours working on assignments/revision.
Quite a lot, I will generally head to the library after lectures and stay there till at least 6:30-7 but then I only really have 2 full days a week so the odd day I will stay at halls and do nothing :P I also never work on the weekends which is probably something I should change up going into exam season and second year as I do then