Are there any commands that can be used to find out certain biomes, such as coral reefs
No, it does not exist.
No, unfortunately not, but you can search for Seeds on the Internet
There's no https://minecraft-de.gamepedia.com/...com/Befehl for it, but you can use https://minecraft.gamepedia.com/....com/Biome with the https://chunkbase.com/apps/biome-finder of https://www.youtube.com/...cromancero.