Humans, male and female, are not neotenous. We have numerous paedomorphic traits (acquired at different points in our evolution) but the relative paedomorphy of traits reflects differing selective pressures through human evolution not a neotony event.
This is a fine distinction; and I'm not convinced by your selectionism. It is at least plausible that (hormonal?) changes favored because they produced one selectively advantageous pedomorphic trait could as a side-effect have induced another which was neutral or even somewhat disadvantageous.
Hairlessness could be non-adaptive, but I find it unlikely. If hairlessness was a neutral trait we'd expect it to be more randomly distributed through populations.
Not neceassarily. Consider the possibilities that (a) it was a side-effect of an adaptation for a non-neutral trait, which is what I suggested; or (b) it got fixed at some time before the human population was small and undispersed.