With regard to your Brit friend in BC - if still on a UK passport and without a specific visa, he must get one of them visitors green card whatsits in his passport BEFORE attempting to clear US customs in an aircraft. With one of those in place and advance notice, there's no problem with cross border pleasure trips for UK nationals. Without, there's all sorts of issues - I had an interesting wrangle last year myself which involved a bit of to'ing and fro'ing over the border in a 172 between Vancouver and Bellingham.
They'll issue these at land crossings but not at airports, so if he's intending flying from Vancouver a quick drive down to the Peace Arch and back would be advantageous before hand, it doesn't take long.
Despite our problems, we found Bellingham customs to be very friendly and helpful, unlike their immigration brethren at the land crossing (the airport chaps were keen to point out the distinctions between CUSTOMS and IMMIGRATION staff - "We are NOT the same!")
Cheers,
SSS