Admin privileges and api access for custom fields

Admin privileges and api access for custom fields

I have a professional account. I need assistance for two points.

1. I am developing a web application to integrate the existing professional ZOHO account. i also have created a demo basic account to test a new application which is being developed by my developer. So, i wanted to know if i can have a demo account where i can use the all administration privileges similar to my existing professional account? The reason i want this is, i can not use the existing professional account for testing the new application being developed.

2. Another point is, i want to use the custom fields addition (specifically for account management) facility through API. Is it possible to create new custom fields through API?