How can I set hours to 48 hours per week? 10 for M-TH and 8 for FR?

You only have a choice to make it a fixed hours per day. In client, go to admin preferences, time periods and change to 10 hours a day. That will give you 50 hours a week I know, but don't think you can set 10hr days, but 48 hour week. In the web you can most likely do it via calendars, but it will be tedious.