To your point, this is kind of an involved question. The various trade-offs get into what kinds of liability protection is extended to owners, what types of corporate structures are dictated by the state the company is formed in, how income is distributed and treated from a point of taxation, etc.
First, to get one thing out the way, nothing prevents you as an owner or stockholder of the company from getting sued no matter what type of legal structure you put around the company. That is, you can't prevent anybody from suing you, because anybody can choose to sue whom ever they want and it is not uncommon for such persons to sue both the company and owners of the company individually. With that said, the primary protections you are probably looking for here are relative to debt obligations of the company being insulated from personal holdings. Getting such protections and having multiple owners rules out the simple structures of sole proprietorship, and general partnerships. Therefore, this puts you into one of the follow types of structures:
The LLP type, gets you the main liability protections of a corporate entity type structure, but still distributes income like an ordinary partnership and also gets similar tax treatment. That is, partnership income is divided up amongst the partners based on ownership percentages and taxed directly as personal income. Law firms and medical practices commonly use the LLP structure.
The LLC or Corporation structures are used for most other business types. These structures create a completely separate entity of liability, income generation, and taxation. These structures also introduce the notion of retained earnings held within the company and the ability to carry forward losses into future tax years, etc.
The standard "Corporation" is a more rigid structure in each state and there are specific rules and guidelines to how the company is formed, what type of "roles" must be defined (like treasurer, secretary, etc.). The LLC is a similar kind of thing, but the charters of the company can customize almost all aspects of formation and exactly how the company is setup. Think of the LLC is a much more flexible version of a corporation.
It's pretty common that new product or software companies are now formed as LLC unless somebody is really hung up on having a "Inc" at the end of the name. I am not aware of any specific advantage of a traditional corporation except that perhaps more people are familiar with them. Certainly, the newer LLC form is much more flexible and customizable in how it is defined.
Finally, while your desire to save money and avoid a lawyer is somewhat admirable, this is not a place that I would recommend to do that. Discussing the specifics with your exact situation with a lawyer and getting a recommendation is not really going to cost you all that much money and you really do want to get this right. My suggestion is to first read up on this topic as much as you can, going to the lawyer as informed as possible, tell them what you think you want them to do, have them advise on your selections, adjust as necessary, and then have the lawyer do the filings.
Note: Assuming that you are going to end up with an LLC or tradition Corporation, the other thing you are going to want to have drafted up is some sort of stockholder agreement that puts some of vesting schedule on the "founders" shares. See this for why.
