I don't follow. Both 1 and 2 seem singular to me. I guess I'll have to walk downstairs and consult the OED.
Yes, I see it can be both. Logic doesn't enter into this apparently. Swinbourne seems to take the plural from the subsequent prepositional phrase. the "of a number of persons or things". Prepositional phrases ought not to influence subject-verb agreement.
Actually, as I said, I base my rule on Inspector Morse. The "not one" meaning seems to cover the situation well. In any case, the editor changed my singular to plural and I changed it back (twice). And would do so again.
Which is not to say I don't use the plural when I'm speaking.
Re Wiki article: This deals with usage, not sentence logic. For that matter, the OED does, too, at least in the examples it cites. I tend to get a bit hung up on grammar rules, having been raised with Latin. :) Also the contraction "none" seems to be based on "not one" and not on "not any".
However, quite right: casual use seems to prefer the plural, if for no better reason than to avoid the "his/her" problem in PC English.