I'm from new orleans, mostly..
Vegetarian food can be found in the marigny, up frenchman (I can't remember the name), and a few scattered places. it is the exact opposite of a veg-freindly town, unless you eat thai, or indian, both of which are not very widespread.

Now, I left 4 years ago, pre-katrina.

It is an awful city to bike in. Crime is widespread (this means you), streets are terrible (worse than 3rd world) and it's hot as he77, and doesn't cool down at night.

Michael's bicycles may still be on frenchman, also.
ride the streetcar all the way down St. Charles, it's a dollar.
you may prefer the lower decatur/marigny to the bourbon/upper quarter scene.

there are a number of beautiful plantations around the area also.

Good luck!