I see you have posted several times but I'll just start here :)
By skin, I take it you mean your skin? In theory all octopuses should be able to bite us. They have a tough sharp beak. However, I have never had my skin broken. Then again, I like to think i have been quite sensible most of the time :)
I have given octopuses and cuttlefish that I have kept as pets, every opportunity and some have tried to bite and felt like a scratch or nip.
If they do bite and break skin it will possibly be sore depending on species
may be as bad as a wasp sting?
You need to use your own discretion and common sense if putting yourself in front of a live octopuses beak! Different people have different reactions.
All octopuses are venemous, they use that to kill their prey. They are not poisonous. A poisonous thing is something you can't eat and many people eat octopuses.