Mapping SQL Server integer to Oracle Datatype
I don't see any reason to not use integer in Oracle. It will be mapped to the approriate Oracle datatype but keeps the DDL at least somewhat portable. 

I also always use VARCHAR instead of VARCHAR2 as they are equivalent anyway. Oracle does not recommend this, as in the future this might change, but this has been true since version 6, so I doubt that it will actually change at all ;)