Regarding RPC nodes, I'd recommend using:
As for the Custom JSON portion of the wallet - that section of Vessel is different than the account's JSON metadata. Each account does have JSON metadata to set things like display name and avatar, but that's a totally different beast than the customjson operations that the specific section of Vessel you're referring to was designed for. That tool built into Vessel was more of a developer tool to write custom operations, sort of like steemengine and steemmonsters uses, as opposed to the information on an account itself.
RE: Vessel 0.2.8 - Bug Fix