I can answer some of your questions:

An Oracle specialist is the database King! Oracle is 100% more complex than MS Access, and I would say any specialist of Oracle is a specialist in any DBMS.

As for MS Access - grab a book and learn it on the weekend, its very trivial. I also read somewhere (awhile back and can't remember the link) that Microsoft recommended using MS Access for testing purposes only.. as it isn't a full fledge DBMS.

IF the Oracle guy can prove himself, take him!