We spell the word Faulty exactly the same in the UK as you do in the US. The title "Fawlty Towers" is supposed to be a pun on Basil's surname.
After Python, John Cleese's best individual TV work is definitely Fawlty Towers (which is kind of sad considering it was made way back in the late 1970s) but he has played many character roles in lots of tv shows and movies, not all of them comedies...he played a sheriff in the western movie "Silverado" and he even appears in a couple of the recent James Bond and Harry Potter movies. He says he works constantly because he has a lot of alimony to pay after he was divorced from his ex-wife Connie Booth, who was the American actress who played Polly the waitress in Fawlty Towers.
Apart from the excellent "A Fish called Wanda", and assuming you already know about the Python movies "Holy Grail," "Life of Brian" and "Meaning of Life", I'd recommend a Cleese solo movie called "Clockwise" made in 1986, which is very enjoyable and full of laughs.