You've got a lot of issues to work out. For example, if your business partner is the "idea" person, but they can't actually participate in running the business and contribute nothing to the startup costs, how should you divide the business interest and profits? Should they be a 50% partner, or maybe only a 10% partner, or something in between.
As an LLC, you might be able to walk away from a badly indebted business without losing your personal assets, but this is not 100% foolproof, the veil of the LLC can be pierced in some situations.
You should discuss this with an attorney and an accountant.
