It's not actually bamboo, it just looks like it. It's related to corn. I heard that any odd number of stems in an arrangement is good luck, but not just one stem, which is bad luck. Even numbers, according to this, are bad luck.
But I've also heard that one of the worst-luck numbers in Chinese lore is 5, which is odd, and one of the best-luck numbers is 8, which is even.
Nine is also very lucky. The grouping of 18 could reflect both the luck of the number 8 and the luck of a multiple of 9.
I don't know. I have a few stalks. It's a lovely houseplant to me. I've found they do best in low light and with distilled water rather than tap. Otherwise they tend to go yellow.