Don't forget to look at how well your two families, especially the better halves, get along. A business is a family affair and any tension can lead to big argument and problems down the road. If they are not involved in the decisions, both of you may regret it in the future. Finally, get a business lawyer involved, as they will be able to point out things that neither of you have thought about. It may cost money up front, but will save you both in the future.
In my partner venture, we used a lawyer to set up our LLC, and, as you said, it was a good investment! For example, he is the one who gave us the advice about the life insurance policy, one I especially remember. His fee was only some several hundred dollars.
Additionally, when we had to borrow capital from the bank, the operating agreement and the insurance policies were key components of our loan application that made a difference to the bank.
He was our corporation's agent, and when we received a patent infringement inquiry letter, he was copied, and immediately was in a good position to help us respond professionally and effectively.
Good luck to you and your partner. I am sure that together you will have a much better and more successful business than would otherwise be possible.
