You can place whatever fields you want into the email form. You just need to keep the hidfden fields at the top so that the Bravenet processor knows whose form is being processed.
You can create as many forms as you want. If you want them to go to different thankyou pages afterwards then you need to code that page as a hidden field in each form instead of specifying it in the service.
As Stephen's response suggests, there is rather more to email forms than just copy and paste into your site. You need to take the time to learn the html.
