Selecting a different theme for specific pages

I have a two part problem.

1) I am using the Default WordPress them and have galley2 installed (using the Ice Theme). I have them linked by the WPG2 plugin. I would like to use another theme only when the gallery is being viewed, and keep the default for all other pages.

2) The other theme I want to use for the gallery will be modified version of the default kubrick. I want to make it a lot wider so it can fit the gallery. Currently the gallery comes out from the edge of the “main column”. Would I do this through the css (what sections) or some other way? Is auto-resize possible?