A Chinese friend told us 168 in a kids hong boa at Chinese New Year means money throughout the year [the Chinese kinda sounds like it] - she also said she never spends all the money on the kid but buys something for them and spends the rest on raising her child [smart cookie]
Also the money should be brand new - which is easier for expats to do than local Chinese as banks are nicer to us :)
Finally for weddings, it's 200 for people you know well and 100 for acquaintances