Oracle iSetup

[Vijaya]

Looking for answers for the following questions?
1.Is there Module Sequence required in iSetup.
2.Can the setup be migrated to specifics Operating Unit and not across operating units.
3. What are mandatory set ups which would not require any buiness information where we can identify and justify them.
4.Any limitations/ advantages of this Isetup tool.
5. What is DBC file.

Thanks