Ok here's my feedback:
1)Around 30 minutes. Since she is only seven years old and in the second grade, I'd say that's good enough.
2)A mixture of all three
3)With an exception to Arabic and Social Studies(also in Arabic)for which reason my daughter has additional tuition, all other homeworks are done completely independently.
4)Yes..to a great extent.
Hope I helped..and a happy weekend to you!