Editing the plugin

When you create an event, in the event setup, there is a tab, where you check what primary fields you want on the form. Uncheck all that you do not want. The plugin only must have First, Last and email, all others are optional. To add fields that are not in the primary list, there is a menu option for custom questions. Go to that and select the event and add any custom questions you want on the form. Custom questions appear on the form after the primary questions.
For fees, you can make fees for any type such as adult, child, early registration, late registration, whatever you want in the fees menu.