If a person is called for an Aliya, does he have the "right" to read his portion if the Baal Keriya also wants to read it. In other words, is the Oleh called to read -- but then appoints the Baal Keriya as his agent to do it for him? Or is the Oleh of today called up simply to make a Bracha -- and then stand there like an illiterate?

This depends on local custom. In Israel, in many synagogues, especially Sephardic ones, it is customary for the Oleh to read if he wishes; however in most places outside of Israel this is not the custom, and it would be disrespectful and insulting to go against local custom.