1 and 2 I think have pretty good consensus. The Bering land bridge opened about 10,000 years ago while the Polynesians didn't reach Hawaii until 900 ad, so if they got to South America it was probably after that. There is some speculation that some separate group of people crossed over even before them since evidence shows that the south American coast became populated very quickly after the Bering bridge opened. Like they got to South America before they got to the interior of north America. That could be because the Rockies are large and without the fish that those people were probably eating, or it could be that some very early people, millennium before the Polynesians domesticated coconuts, made the crossing. That theory of very far in the realm of speculation but it's a fun theory.