No one can give you the answer. There are so many variables.
Use the search function on this site to search pricing threads. There are literally thousands to choose from that can give you lots of information for future use.
Lots of research about starting a business is absolutely necessary to starting a business. It's not all baking and decorating. There is paperwork - health department regulations, taxes, marketing, customer service, emails, phone calls...
Research your local laws, get legal to bake and sell, and please, for Pete's sake, don't intentionally undercut other legal businesses. It's unethical and unfair to the businesses who worked hard to get where they are. They may truly...
I make my own, and use store bought. Buy whatever is 'cleanest.' Pure vanilla, not a bunch of additives. I always read the ingredient label, and research the company I buy from. (I research mainly out of curiosity)
That's a tough question. It's really none of your business, what she does with hers, so she is not obligated at all to discuss it with you. You are an employee, not a partner.
When the time is right, I'm sure she will approach you to have the conversation. She may be trying to figure out herself, how she wants to handle it.
Bummer. Your 'about us' sections states clearly that you are home-based. I know not all potential customers would look at that, but it's there. I'm no site wizard, and don't pretend to be, so I can't give advice on your page.
She has an issue with a home-based business - sounds like a personal problem.
Delete delete delete!! Do not let a nasty comment stay on your page for a second! It's your page, your business.
I she goes crazy over it, so be it. Let her throw a tantrum, but don't let her nastiness stay posted for other clients to see.