I was on facebook but im no longer there however I would go for the UK one as when I joined one of my close friends from Canada popped up so it would appear to be Universal -in saying that if you live in the US then sign up for the US version .
There's only one facebook site - when you sign up i think it asks you to put what country your from.
Anyone in the world thats signed up to facebook can contact you.
word of advice -
If you don't know the person who requested to be friends, don't accept them.
There's some weird people in this world. so please be careful
I could have sworn I answered TB and lil -anyway -sorry had to make a hasty retreat from FB and crucially the CB site.
I didnt know who had my details or indeed were friends with this particular 'person' but just had to do a blanket delete.
Will open shop again soon -I have friends abroad who I kept in touch with as well as other friends -yourselves included so dont be alarmed if you receive a friends invite -its just me getting rid of the dross and staring again lol