iOS xcode version compatibility with ios version

I have xcode 3.2.3 and want to run an application for ios6.
my question is:
1.Is there any way to run ios6 app on xcode 3.2.3.

2.And im thinking to install xcode 4.5.2, will it support application for ios 4.3 and above versions?
if yes then what all the SDK i require? can i download it separately or they are available in xcode 4.5.2?