New Seller Advice

Me and my wife started Amazon a month or so ago and sold a couple of items already. We are considering doing this seriously and launch a small brand sometime this year.

My questions, if any of you more experienced can help with please:

We are currently doing it as a Sole proprietorship, should we create a LLC? Any unforeseen issues with either one? How to track sales and expenses? Any low cost software that can help? QuickBooks? Want to apply for Sales tax permit (in TX), is it better to have it tied to personal SSN or LLC EIN (forcing us to get an LLC)?

Any help would be greatly appreciated. There is so much information and so much to learn, I am completely overwhelmed. TIA.