Questions about migration from 11.1.0.7 to 11.2.0.2 using datapump

I am testing the migration of our PROD database from AIX 5.3 on 11.1.0.7 to Redhat Linux 5.5 64
bit on 11.2.0.2. I am performing the migration using expdp and impdp. There were many missing
SYS grants after the datapump import which was run from the SYSTEM account. I have
restored most of the grants, but there are 4 packages in the DMSYS schema which are invalid,
but since the packages are wrapped, I cannot see the code to figure out the problem.

I have several questions:
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1.  Can the database files simply be copied from the AIX server to the linux server to migrate?
   (I believe the only method to migrate to new O/S is create an empty DB and datapump import. Please confirm.)