I've been off chasing stomatopods and blue-rings for the past month, so I missed most of this thread while it was developing. However, a few comments.
First, thousands of blue-rings, nearly all H. lunulata from Indonesia, come into the U.S.A. every year. You can buy them from several importers for from $20-60 each. Most are adults, many have been captured using toxic chemicals, and you will be lucky if you can keep one alive for a month or two. Most die in days. Even if they were not potentially deadly, they are not a good deal.
After having seen many of these animals for sale - including in local retail operations where the owners had no idea how dangerous they were, I tried to provide some warning about purchasing these animals by posting to various on-line groups and by writing a piece for the aquarium magazine, FAMA. Unfortunately, that article seems to have stirred up more interest in owning blue-rings than it did in deterring people. (The article - sans pictures - is posted on the Cephalopod Page.)
The primary toxin in blue-rings is TTX, a common biological toxin that blocks neural conduction by interferring with sodium channels. Blue-rings themselves are NOT affected by TTX because they have a modified sodium channel that does not bind with TTX.
The question about whether this is a venom or a poison is to a large degree semantic. However, I would not advise eating a blue-ring. Fugu poisoning is simply TTX that was not removed from a pufferfish. Obviously, ingesting TTX in this case is not beneficial to your health. I would suspect the same of eating a blue-ring. While we don't know for sure, the aposomatic warning coloration of blue-rings is just as likely saying "Don't eat me" as it is saying "Stay away or I will bite you". I have watched fish spit them out quickly. Again, I haven't tried it myself.
I have experience some neurological symptoms from blue-rings, however. When they die, they leak saliva into the water and this does seem to penetrate the skin. It produced only mild tingling, but I would not like to take a bath in the stuff.
The sequence shot for Incredible Suckers was staged and did claim that the blue-ring released venom. There is one paper claiming this. I have tried to replicate it without success. The person who filmed the sequence admits that one stomatopod pounded the octopus and that the sequence was shot in a tank. I suspect that the octopus was damanged and "leaked" saliva.
As for inking, it is diagnostic of blue-rings that adults do not ink.
Roy
