Hello Justinxiamen, welcome to the forum. I think I can guess what is meant here but just to be sure could you give a little more context. The more context you give in the forums the more chance of a meaningful reply.
Also it would be better to ask your second question as a separate thread
'Here's to us' is an idiomtic phrase which is more commonly heard in different ways when people are 'toasting' each other with a drink (a practice which is common in Hong Kong I believe). They might say 'Here's to you', toasting a friend or 'Here's to the bride and groom' toasting the newlyweds. Alternatively someone might say 'Here's to us' thus toasting everyone present. In all cases the implication is to wish those so toasted 'much luck'. When the robber says this on the train, although they are not drinking, the sentiment is the same. It is a 'drinkless toast'.