Cascadia

Normally, yes. Before choosing, you may spend a Nature Token to take any tile and any token from the display instead (p. 6).

No. It only has to touch at least one tile already in your environment; matching terrain matters for scoring, not placement (pp. 7–8).

No: a tile can hold at most one token, and the tile must show that wildlife as an option. You may place the token on any eligible tile in your environment; if none is available, return it to the bag (p. 7).

If all four match, replace all four automatically. If exactly three match, the active player may choose to replace those three, but may do this only once on their turn (p. 6).

Before selecting a pair, spend one to take any displayed tile and any displayed token, or to replace any number of displayed Wildlife Tokens; you may spend multiple Nature Tokens in a turn. Each one left at game end is worth 1 point (pp. 6, 8).

The game ends immediately after a turn when there are no face-down Habitat Tiles left to refill the display. Each player takes exactly 20 turns (pp. 5, 8).