New Orleans is of course amazing. The French Quarter is full of hobo kids as well as drunken vomiting tourist frat boys. A friendly place. Don't let the bullshit about ever since Katrina it's been very dangerous scare you- yeah there are gang war neighborhoods , but if you just hitchhike in you can hang out in the French quarter and be fine. Seriously, even if you are in a gang neighborhood people leave travelers alone- you have a bag/backpack and a cardboard sign- you're basically homeless- you don't belong anywhere/you belong anywhere. Don't worry about bad neighborhoods- you're a bum!
Loads of free food serves in New Orleans if you're into that sort of thing, I hear the Hare Krishna dinner is even better than Hare Krishna dinner usually is and they basically leave you alone religiously unless you're actually interested.
Oh and even if you look like you're 12 years old you probably won't be carded at all and you can drink in any bar you want. If one place cards you just go to the next place, you can definitely get drunk in New Orleans no matter who you are if you have money. New Orleans loves a drunk person and drunk people love New Orleans.
And it's not about Mardi Gras anyways. That's kinda for tourists and kinda too much. New Orleans is a constant party whenever you go. People get off the boat or oil rig they're working on, come to New Orleans, blow all their money, and by the time they're done spending their money they're ready to go back to work on the boat.
I recommend going to The Abbey bar on Decatur street. Ask for it everyone will know where it is. Just a really good dark and comfortable bar, often seems to be full of hobos.