You can now create custom fields for and collect additional data for jobs. Whether you wish to create a text field, or a dropdown field, details makes this easy.

Can data from these custom fields be used to customize emails and documents?

Yes, all custom fields within details have a template code eg  %T_ELEVATOR%  that will allow you to insert the data collected into template documents and template emails.  This allows you to customize your documents with that particular job data and automates any filling of forms.  

Are details available for Leads?

Details is only available for LEADS only via the Moverbase API.  This will now allow you to create any fancy form, with as many fields as you wish and POST that data directly into Moverbase when capturing leads from your website or elsewhere.