Hi, I. Blue. As always when I hear about people forming guilds, I first want to thank you for your enthusiasm and willingness to lead. It's players like you that keep MMOs in business. So a hearty /salute for that.
Now, to your question: Every guild is of course required by the design of the game to have one player as the guild leader. That player has access to all the guild UI functions, the ability to gkick any other members, and the permission to disband the guild. Beyond that, you can have as few or as many officers as you want. It's entirely up to you.
Tasks and assignments
The question mainly comes down to this: What tasks will the officer(s) of your guild manage? You mention writing up some policies for grouping. Creating written guidelines is an important task. Fortunately, once they are in place, you won't often have to change them or add to them. You will, however, have to enforce them, interpret them when necessary, determine the truth behind any drama springing from them that you didn't personally witness, and (where appropriate) dole out stern words or even punishment when people violate these guidelines.
Some other potential tasks for a social guild include recruiting, bank/gold management, mediating disputes between players, organizing activities such as dungeons, raids and Battlegrounds (if you want to), and inviting and kicking players.
If you think you can handle that all by yourself, then you don't need any other officers. However, what starts off as a few simple tasks can become overwhelming as the size of the guild grows, so keep an eye on how much time you spend on leadership duties. If you think it's too much at any point, then you'll want to promote some officers and assign them to specific tasks. That way you won't have to shoulder the burden all by yourself.
Benefits of multiple officers
Don't let me talk you out of going it alone if that's what you truly want. I will, however, point out a few benefits to having more than one officer.
Other officers can be online when you're not. Having at least one officer online is helpful for a few reasons. They can invite players who have been accepted as members to get them on the roster right away. They can answer questions from nonofficers. Finally, they can be a witness to inappropriate behavior that might concern the guild's leadership when otherwise it might have gone unnoticed.
Another officer can also provide a different perspective on a tricky issue. It's helpful sometimes to bounce ideas off of someone else who's privy to the same information you are.
More officers can organize more events. It doesn't sound like you're planning to provide organized guild activities. If you ever change your mind on that, having some more officers to help out can allow you to provide more and better activities for your guild.
In the end, however, the decision -- and the ultimate responsibility for this community -- is yours alone.
Recently, Officers' Quarters has examined how strong new leadership can create a guild turnaround, the pitfalls of promising more than you can deliver, and lessons learned from Scott's own guild demise. Send your own guild-related questions and suggestions to firstname.lastname@example.org.