Cascadia

You normally must take one of the four displayed Habitat Tile + Wildlife Token combinations (you take both together); however, before selecting you may spend a Nature Token to take any one Habitat Tile and any one Wildlife Token separately. (p.6)

Yes — you may place the Wildlife Token onto any single Habitat Tile in your environment that shows that animal and does not already have a token, including your Starter Habitat Tile or the tile you just placed; if you cannot or choose not to place it, return the token to the cloth bag. (p.4, p.7)

No — the only placement requirement is that the new Habitat Tile must touch at least one side of an existing tile (or the Starter); matching terrain is not a placement rule but is used later for corridor scoring. (p.7, p.8)

You gain a Nature Token whenever you place a matching Wildlife Token onto a Keystone tile; before selecting you may spend Nature Tokens to either take any one Habitat Tile and any one Wildlife Token or to wipe/replace wildlife tokens in the center, and any unused Nature Tokens are worth 1 point at game end. (p.7, p.6, p.8)

If all four visible Wildlife Tokens are the same they are automatically wiped and replaced one‑at‑a‑time from the bag; if three are the same the active player may choose (once that turn) to wipe those three and replace them, and wiped tokens are returned to the bag after replacement. (p.6)

The game ends immediately if, at the end of any player's turn, there are no face‑down Habitat Tiles left to replace the one taken; as noted in the rules each player will play exactly 20 turns before final scoring. (p.5, p.8)