I honestly forgot to edit the Master Sword part out. I had to use an older version of her bio for this which I forgot to edit.
And on the subject of Link's immortality, Navi's growth, their appearance in a Hyrule thousands of years in the future...that stuff all takes place within the story that Karin is eventually going to be a part of.
Link's immortatlity is the result of his marriage to Navi. (Prepare for lots of fanon) During the Fairy Unification Ceremony, a ceremony used for any interspecies relationship involving fairies, half of the said fairy's magic is passed over to their mate. This essentially binds the two's life spans. As long as Navi lives, Link lives.
Navi's growth is more of a quick explanation. In the (fanon) aftermath of Majora's Mask (of which it is never explained how Link and Navi reunited, hence keeping all those complaints about my alteration of it subdued), they have been romantically involved thanks to the Great Fairy's ability to enlarge Navi within the fountains. This led to, well, stuff that couples do when they're really, really close.
During that time, Saria and the other Sages had managed to concoct a potion that would permanently simulate the effects of the Great Fairy Fountain on Navi's body. She drank it and got big.
The residing in the post WW Hyrule is a much longer story. Let's just say that their accidentally stumbling into it directly relates to Zelda becoming the villain.
And depending on what timeline theory you believe in,
LoZ and
AoL take place after WW. And why wouldn't the Kokiri be weak to fire? They were born from the Deku Tree, so wouldn't that make them part plant?