2 Questions..

1. How get chunk on which you stand?
2. How to realize: Player came to spawn territory (or other chunk) and he get message: "Welcome to spawn"?

idk how to, but i know it's possible.

for the second thing: eg look at factionspro, it has areas & notifications on enter

Thank you!

No. It is $player->getLevel()->getChunk($player->getFloorX() >> 4, $player->getFloorZ() >> 4)

Thank you. And how I can get chunk id? Example: 89,25

Isn't that the chunk ID?

Sorry. I didn't know one thing. I looked at the WorldEdit (CraftBukkit) code - I learned as they get that "ID" of chunks.

PHP:

$x = 500; // Player's X position
$z = -120; // Player's Z position
$chunk_x = (int) round($x / 16);
$chunk_z = (int) round($z / 16);

That's wrong. You should use >> 4 not / 16, because bit shifting is much faster than division. Also, it should be floor not round. And what do you think happens if the $x and/or $z is/are -1? If you use bit shifting, you need to neither call functions (thus prevent some overhead that is fixed in PHP 5.7), nor to do rounding and division. I am not sure if it works well for extreme coordinates like those in the farlands, though.

-1 >> 4 is still -1 which is what you want. If you want to reduce stuff you can skip the round or floor. $x >> 4 is an int operation only so an int stays an int (no need to floor or cast to (int).