The number it can hold is completly dependant on how long the names are. The variable cannot hold . 941 characters I mean, thats about 92 nicknames of 10-letters each.. The proof:
//set %abc $str(1, 941)
(no error)
//set %abc $str(1, 942)
* /set: line too long
As for the /'s, they ar enot neccisary, but i use them just so i'm in the habbit. I used to go without, but then i was doing ns identify in the channel without the /'s too and got myself into trouble.. *oopse*
Also, the variable unsets itself after 10 minutes. This means if they deop someone, wait ten minutes, and deop another, it on;ly counts as one deop. Thats what the -u600 is for >:F