I have just caught up with this thread and since no one seems to have answered one of Czerny's first questions:
QUOTE(Czerny @ Dec 29 2010, 12:46 PM)
One I'm less sure of is the precise usage of who / that / which, so if anyone has any handy hints for that one it would be appreciated.
When I first started teaching English as a foreign language this was one of the points I found very complicated.
The most obvious difference is that you can't use "that" in a non-defining relative clause (but as a native English speaker you probably wouldn't make this mistake anyway). So, for example, you can't use "that" in the following sentences:
"My neighbour, who is very house-proud, spends three hours a day doing housework."
"His new book, which was published in June, has sold over 100 000 copies."
If you want to be strictly grammatically correct, you ought to use "that" (not who or which) when talking about something/someone which is unique so:
"This is the best book that I have ever read."
"The only time that I saw them was in 1988."
These examples are not particularly good as you don't need a relative pronoun but I can't think of anything better as I'm typing.
On the subject of American/British English; when I was at school I had an English teacher who objected violently to the expression "train station" and insisted on "railway station". His reaction was so extreme that I still avoid saying "train station" but last week I flew into Gatwick Airport and noticed that all the signs were to the "train station." I can imagine him (if he's still alive) demanding to see the airport manager...