Default area

My company is planning to use single TFS2013 project.

We have 10-15 applications; some of them have code under TFS2012 source control. The others have source in different plat forms like mainframe of source safe.

In TFS2012, we added customized field (application).

In TFS2013, we think to use area to separate WI between applications. My questions:

1. Can I create AREA in the same level as the TFS project default area? IE it is not a child of default area.
2. Can I somehow map source control to match areas?
3. Can I have different teams assigned to different areas and restrict them from use other areas in the drop down list in different WI?

In summary, it may looks like have different TFS project under a single TFS project.

Thank you