The best response I can give to you has been elaborated on in previous threads. I would encourage you to utilize the search button (right top area of page, 5th blue button from the left). This discussion cycles with time and has some helpful information.
1. Best advice from me is to do your homework (as you are right now). Research and learn from other Entrepreneurs with business models such as Nx Level (through the Small Business Association or SBA), or others such as SCORE.
2. If you need to know about liability then a lawyer is the one to talk to.
Let us know how you are doing and how we can help.
Night