5 Lands Korvold, Fae-Cursed King decks that are built around lands are generally playing lands that sacrifice themselves to fetch lands out from your library
The question will come down to the tap ability, on the one hand, which is good but is a tap ability, and whether or not Naya is better than Kadena, Slinking Sorcerers Sultai
By now, experienced fans have been playing MTG for ten, fifteen, or even twenty years, and will have a collection of valuable cards to prove it
If you don't have a land in your opening hand, mulligan
Fyndhorn Elder is basically a more expensive version of Fyndhorn Elves, except he's a bit bigger and adds two mana
That would be quite a larger number, but imo still small enough that they would be scarce