I’m in the beginning stages of starting my FBA business. What should my store look like?

I’m just starting to sell on Amazon. I’ve been reading some books and watching videos and finally have pulled the trigger. I’m waiting for my first few product samples to come in the mail. I understand that this isn’t a quick money scheme and it takes a lot of upfront work. I’m curious on what your stores look like. I don’t need to know your actual product but I’m curious if your products are all similar, different, or do you just keep to one product. I actually have two products I’m hoping to come in, but they are very similar. Is it feasible to grow your business with many different products? I’m just trying to think about the future. If my product stops selling can I go in a completely different direction or should I remain with different, but similar products.

Also I’m starting with only only 200 items to sell. I’m starting small before I dive in. I’m hoping to use all money made to slowly grow. I won’t start paying myself until I feel comfortably established. It would be cool for this to become a full time job, but for now it’s a side hustle. Is this possible? I’m ready to start grinding. Also is there any place I can look to get an idea of Amazon fee’s? If you have any other advice please feel free to share.