As maid of honor, you are the bride's right-hand "man" on the wedding day. If the photographer or caterer has a problem, s/he should go to you or the best man, not to the bride and groom. The bride and groom are stressed out enough
and part of your job is to make sure they can enjoy their day and focus on each other and the life they're starting together, not on whether the little lamb chops are warm enough.
You should take the lead in planning a shower and/or bachelorette party; the other bridesmaids should help. Ask the bride what she'd prefer... a dinner out, a visit to a Chippendales show, an afternoon tea, etc. Showers are never given by the bride's relatives, but since you're a friend, you're ok on that score.
During the ceremony, you may have to help the bride keep from tripping over her train
and you will probably hold her bouquet as well as your own. You may be asked to sign the marriage certificate as a witness - depending on what state you're in. If it's a religious ceremony, there may be a marriage document that you may be asked to sign as well.
During the reception, you can give a toast if you wish. You will probably also dance with the best man. You may also be asked to keep half an eye on the gift table, or keep track of important items (rings, marriage certificate), etc.
HTH