Your OS authorities don't matter to DB2, which has its own authorization mechanism, although it is based on the OS authentication. In other words, you must have a login ID in the OS, which, if you are successfully authenticated, will be used to determine what authorizations you have from the DB2 point of view. You can read more about the model here: http://pic.dhe.ibm.com/infocenter/db2luw/v10r5/topic/com.ibm.db2.luw.admin.sec.doc/doc/c0021804.html
At a minimum after installing DB2 and creating an instance you will have the instance owner user that has sufficient authority to create a database. The creator of the database, in this case the instance owner, automatically gets the SECADM (security administrator) and DBADM (database administrator) authorities over that database, which allow that user to create objects in the database and grant various privileges to other users.
sudoer rights in the OS you can
su -l to the instance owner user (might be
db2inst1 as this is the default) and perform whatever job you need.
As for the database migration tools, consider the IBM Database Conversion Workbench, which is a freely available plugin for IBM Data Studio that is also free.