For the first point: The skull kid seems completely oblivious to Link during the last half of the final day when looking at the moon for the tear. I don't believe the skull kid was trying to smash Link with the tear. I mean it wouldn't be the first "inconsistency" when you think of events such as Mikau's death.

For the second, that's an interesting idea with the whole Saria thing. I suppose it could be possible but it would seem kind of strange, assuming Link returned to the point in time directly before pulling the master sword from the pedestal (which makes more sense to me since he'd be stuck in the temple behind the door of time if he were to return to any time before he opened it), since they would have probably met on at least two occasions before in the lost woods (mask sale and heart piece) without him recognizing Link. Then again, maybe the skull kid in question is a completely different skull kid that we hadn't met in OoT and Saria just taught her song to every damn skull kid she met LOL.