You can start a business account with your SSN if you are an LLC, or with a Tax ID if you are a business.
No - there is not. Verizon does offer special price plans, device pricing and discounts on service to business customers who have 5+ lines and sign an account agreement.
Your plan will not change at this time. In the coming months you will receive information regarding any changes or options that will be available to you. Verizon is currently evaluating your plan to offer you valuable solutions.