If you go to “Users” -> “Profile fields”, you can add, edit, and remove profile fields. There you will find a field called “I am a”. If you edit that field, you can change the drop down values from Man and Woman, to Byer and Seller. You can also click the blue “Add new field” button at the top of the page and add your own custom fields, such as “production of” and so on. This should answer a, b, c, and d. I’m not sure what you mean with e. Regarding f, most likely, but the only way to get a definitive answer is to test it.