ນ້ຳມາປາກິນມົດ

No, it is also very common in Thailand (in Thai: น้ำมาปลากินมด น้ำลดมดกินปลา) because of the shared cultural and ecological history of the Mekong.

Yes, but it might sound a bit dramatic. It's usually reserved for more significant life or social changes.

In this context, 'lot' (ລົດ) means to decrease, recede, or drop in level. It's the same word used for 'reducing' a price in a shop.

Not inherently, but it can be seen as a 'threat' if said directly to someone in power. It's safer to use it as a general observation.

Because they represent the two extremes of the Lao environment: the dry land and the floodwaters.

Technically yes, but the standard order is 'Fish eat ants' first, following the natural arrival of the rainy season.

The vocabulary (water, fish, ant, eat, come) is A1, but the metaphorical meaning is more advanced. It's a great 'bridge' phrase.

ນ້ຳມາປາກິນມົດ ນ້ຳລົດມົດກິນປາ.

It isn't a religious text, but it perfectly illustrates the Buddhist concept of impermanence.

There isn't a direct opposite, but 'Pa yai kin pa noi' (Big fish eat small fish) describes a permanent state of inequality rather than a cycle.