I suggest you get hold of some of the forms that he is likely to encounter when he arrives in the US: opening a bank account, getting a mobile phone, etc. You can ask him to fill them in and go over the language together. Even advanced students have difficulty with the sort of language you find on forms of this sort.
You can also do a lot of authentic listening practice. Get hold of real recordings - either audio or visual - and build listening activities and language practice around those. You can also work on pronunciation, especially understanding how sounds are produced by native speakers in a familiar situation.
Hope this helps!