>>>Is an editor supposed to search for new pages to add or just review the requests that come in?<<<
Most submissions to the ODP are secondary and even terciary to some editors. Editors should find new listings by searching engines, phone books, billboards, newspapers, and any other means to find possible listings if editing time allows it.
ODP's search feature has been "rolled back" while the upgrade is ongoing. Sites may very well be listed and not showing as so.
>>>This specific category already has an editor. How does this work?<<<
Because a category has an editor listed usually doesn't affect an application for a new editor, or show the level of activity of a current editor.
My only suggestion about applying is the "make sure you read_and_understand the guidelines" , especially the section concerning Titles and Descriptions.
Looking at the title and description for the one you submitted, it is "my" opinion that it definitely needs to be revamped to comply with the guidelines. Lose the hype, advertising, and only the "proper title" should be in the Title box.
Good Luck!