This is in reference to the form field(s) breaking out on the side of the page based on the email you sent the other day? I will be fixing this one today which will be an update to the theme.
I have a fix…the form fields will be more responsive, along with an update to the form code template as well. I will upload an update to this theme later today as version 2.5.3, along with some other adjustments I am doing.
You can yes… the contact form 7 plugin let’s you add more. I would recommend checking out their documentation for that. Also, any additional fields, use the form snippet code as a guideline as well.