A good person to ask is Ivy (veggie shop, first on left when you leave the ferry pier. She'll explain what the vegetable is and often offer a suggestion for cooking it Chinese style. For example, Chinese celery (looks like a slimmer version of Western) is great in soups and is also much cheaper than the heavy Western style heads. Not really any good as a crudite, though since it's too soft.
Can't give you much advice on seafood. Don't like the stuff.
Good luck!
Sorry, I have just noticed you mentioned meeting like-minded people. Pondering over a variety of veggies from Ivy's often turns into a chat with another customer about who is cooking what tonight. I've had some good suggestions doing that!