Can I limit the available styles from the rich text field?
Redactor is the name of the Rich Text field itself, as this is a 3rd party component Craft has taken great use of!

With Craft you are able to create custom Redactor configurations whereby you have control over which options you would like useable (bold, italic etc), and these can be set on a per-field basis.

Have a look at the Craft site for details on how to set your own custom Redactor configurations: http://buildwithcraft.com/docs/rich-text-fields#redactor-configs

When you edit a Rich Text field in Craft you will see a 'Config' dropdown. These are the files you have created in craft/config/redactor (see above link for details)