Question: When Elliot Spenser is being transformed into Pinhead, who was cutting lines into his face and head and driving nails into him?
Answer: Presumably another cenobite/cenobites. The choice not to show them makes for a better scene, as that moment is all about him, becoming the iconic Pinhead; the cenobites who made him that way are of no consequence to the story, and their own grotesque appearance would have distracted from his transformation.
Question: I haven't been able to find a proper answer elsewhere, so I figured I'd give it a go here: The Arrow Video Blu-Ray version of "Hellbound: Hellraiser II" is getting a re-release in the US soon. (It's the same disc from the 2013/2014-era "Scarlet Box" Blu-Ray set.) Does anyone know if the version of the film on that particular release is the unrated cut? Amazon only says "Rated R" in the description... but at the same time, Amazon also isn't always super-reliable with its information. I'm very interested in picking up the disc since I don't own the film on Blu-Ray, but only want to buy it if it includes the proper unrated cut.
Answer: I jumped the gun and bought it, so I'll answer my own question. Yes, it does have the uncut, unrated version of the film. For some reason, the packaging says "Rated R," but it's definitely the uncut version.
Question: Pinhead and the other Cenobites have no memory of their human lives. When Channard is being turned into a Cenobite, how come he still retains his memories?
Answer: In general, the Channard cenobite seems different from the others. Ex. He seems directly linked to Leviathan through the (rather phallic) stalk/tube. It's entirely possible that his transformation was different all around, and keeping his memory was part of his individual process. Also, there's nothing that necessarily indicates the other cenobites immediately forgot their past lives. It's entirely possible they forgot them over time as they became more acquainted with hell and their new "lives" as "explorers" in the realm of pleasure and pain.
Answer: Probably because he's fresher than the others.
When Elliot Spencer is being transformed into Pinhead, all memories of his human life are immediately erased. The same thing happens with the other Cenobites.
It never shows how long it took them to lose their former memories. Just that it did.
Answer: All we can see (in abstract closeup) is serpent-like tendrils cutting him and driving the pins into his head. As someone else said, it's likely another cenobite, although alternately it could also be the same "contraption" that turns Channard into a cenobite late in the film, given the tendrils are similar to the ones he sprouts.