Haiying,
i think not only in china, foreigners learn first the bad habits!!!
i am italian, but i lived 15 years in norway before moving to china.. experienced a lot of what you say, both on me and just watching around!
about behaving differently than in the home country, also this is completely normal!!
and it applies to every place i hav been and lived.. to every nationality!!
chinese in norway are not like chinese in china (i had a relationship with a chinese girl there and got to know several chinese, both students and workers!).
about what chinese think it is impolite in china and we laowai makes mistake, why don't you have a look at my blog as well (unfortunately you need to jump over the wall!) and your thoughts there as well:
http://aikidude.wordpress.com/2011/03/31/things-impolite-in-china/about the being drunk part.. i remember when i just moved to norway i had been shocked by the drinking habits of the locals: at 3am (closing time of almost all places in norway) all roads were filled by completely drunk norwegians of all ages (from youngsters to grandmas!!!) saying it was disgusting is too little!!
seeing women the age of my mother passed out in their own vomit on the curb was something i did not expect..
so i do understand you!!
about the rude talking.... mmhhh... once one understand more chinese.. wo kao here "ge pi" there.. "sha b*" up and down.. you got your share as well!!
the thing is we do not understand it as easily as you do..

i admit anyway i am learning faster the slang and bad words than the "normal" chinese.. my bad!!!!
anyway, very happy to have locals interacting in these boards!!!!
we wish to have more!!!