Complete Arcane is not clear on the subject, and as you pointed out does not actually specify that you need to assign the +1s, so I'd be up to the DM. But I do not see the relevance? You are arguing about a situation where you enter the class with a multiclass Warlock/spellcaster, where I am trying to explain that there is a benefit gained if you enter as a single-class Warlock. Its not even an analogous situation.
I am sure there is a very interesting discussion to be had about how that works when you enter as a Warlock/spellcaster, but that is not this discussion.
No, you'd still be eligible if you qualified racially.
RAW you are correct, Warlock says you can benefit from the +1 level of spellcasting despite not being a spellcaster, but Human Paragon says if you are not a spellcaster you cannot benefit from that feature. And Human Paragon is the more specific case. I believe most DMs would rule that you cannot benefit in spell advancement from that, but RAW you are correct.