You can be an LLC for state law and a C corporation for federal income tax purposes. The LLC is a state law entity; the entity's federal tax classification is a matter of federal tax law. If you form a state law LLC, you can check the box to be taxed as a corporation and then you would be taxed as a C corporation, but you would be an LLC for state law purposes.
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You need to have him execute a stock assignment of his shares to you. You would want this stock assignment to include some representations and warranties from him to you, such as -- he owns the shares, hasn't sold them to someone else, etc. But it can be a short document. You may also want that document to include a release of claims, in which he releases you from any claims on the business--such as claims for unpaid salaries or similar amounts. It won't take long for a lawyer to assist you...