1. the fact that the 'leader' may have some human traits was already shown prior to the new ending, when he both stood in the sunlight, burning himself, and when he made the trap, all in an attempt to save his (presumably) mate. I even discussed this with my girlfriend after we watched the movie and said I was surprised how they didn't play it up afterwards.

2. Neville dying fits the original story, and this one, though for very different reasons. The fact that he basically fails to cure the infection seems to wound him more than dying to see it actually works (in the new ending as opposed to the theatrical version) He isn't really a legend in the alternate, which doesn't fit, so you're right there.

Like I said, they both could work...I loved this movie up until the woman saved him, but whaddyagonnado.