Hey rob,
I'm not an expert or anything, just an amateur, so take my opinion with a grain of salt if u like, but i figured i would weigh in and try to help if i could.
I would wait to feed him until at least the weekend, give him time to acclimated. You said he had decent girth, so i doubt he's starving. Give him a little while just to get used to his surroundings and become accustomed to you.
As far as his temprement, as strange as it might be, it's not a shocker really. You may have been the first person to ever sit down and try to handle it peacefully and it's recognizing you as not a threat. It's a little unusual that a possibly WC anaconda would have a good temprement, but stranger things have happened lol. Usually a good temprement with this type would mean it's feeling sick and isn't even going to fight back, but with it being curious and active, u may have caught a break so to speak. It seems like it's not too far gone to get this one into a good pet. Your friend getting bit isn't a shocker at all, anacondas hate being put into bags or containers (learned that the hard way lol) for some reason, moreso than most other snakes. You may have already thought of this or someone else might have already said it too, but i would take it in to a vet and get a health check. It's probly got a parasite load, need to get a fecal exam.
You don't have to put them in water, i don't really think it's a MUST, but i do know they like it. It helps adhere to their natural instincts. The thing with Anacondas are that they are most similar in actions to crocodilians in some ways. They prefer to be in the water more than anywhere else, keeping their head just barely over the surface. In the wild, they hunt by waiting near the edge of a watering whole for an animal to drink, grab it and pull it in the water and drown it. It provides security for them and keeps them wet and happy. I would do it just to make ur conda happy, but that's up to you, maybe someone else will have a more conclusive assessment.
Jason
Not from Philly, but luv heavy metal, very heavy metal. What are your favs? Mine are Slipknot, 40 Below Summer, Chimaira, Killswitch Engage, Machine Head, Devil Driver, American Head Charge, Nothingface, Otep, Mudvayne, DKL, Bloodsimple, System of a Down, Bleeding Through, Trivium.....i could go on forever really lol.
I hope the info helps, sorry about what happened, that really sucks. It's people like that that are ruining buying snakes over the net and making it so that nobody can be trusted anymore. Maybe he'll take a long walk off a short cliff...wouldn't that be nice? 