I'm British too so am pretty well qualified on the 'soccer' football debate.
As far as popularity goes there are very few places in the world where it is not the number 1 sport. Apart from USA and Canada I would say India, Pakistan and Sri Lanka where cricket is king, New Zealand and South Africa with rugby, Australia with rugby, cricket and Aussie Rules, Kenya and Ethiopia with long distance running and some of the Asian countries too like Thailand where its boxing.
In Ctl & Sth America it is a religion and for many kids the only way out of poverty. Same story for Africa. Kids cant afford a proper football so they improvise with anything that resembles it. Mexico has the 115,000 Azteca Stadium and in Brazil the 150,000 capacity Maracana in Rio. The 1950 WC final had the largest crowd ever with 205,000 watching Brazil vs Uruguay.
Same for Europe, football is king with only maybe Lithuania the exception with basketball. Basketball is the number two sport in most European countries behind soccer.
The Italian, Spanish, English and German leagues are the strongest and attract the best players from around the world. The best Sth American players come to Europe too rather than play in their own leagues as many of the teams there need to sell to keep the books balanced.
The best teams in each league qualify for the Champions League with Real Madrid the current champions. Other strong teams are Bayern Munich, Man Utd, Barcelona, Valencia, Deportivo, Arsenal, Liverpool, Juventus, AC Milan, Inter Milan, Roma, Bayer Leverkusen.
The offside rule is very tricky to explain.
Its best to sit down with the salt cellar and tomato ketchup bottle on the kitchen table to explain.
Basically an attacking player is offside when, as the ball is played to him from a team-mate, he is ahead of the last defender. If he is LEVEL with the last defender as the ball is played to him he is ONSIDE and play can continue.
What causes so many problems is that the linesman has to look at two things happening at different parts of the pitch. Usually when a player passes to the forward he was behind the last defender when the ball was played (ONSIDE) However a linesman will look up a split second later to see the forward ahead of the last defender and flag for OFFSIDE.
That's what caused so much controversy in this World Cup especially with Italy who had some poor decisions go against them. However FIFA do not want video replays. I think it would be a good idea and a similar system to the NFL could be used when a coach or manager can issue a certain number of challenges per half.
In league games in Europe if a match is tied after 90 minutes both teams get a point. You get 3 pts for a win and 0pts for a loss.
When it gets to knockout football, a tied game will go into a maximum of 30 mins extra-time with the first team to score the winner. This is only a recent rule over the past few years. Before that 30 mins was played no matter how many goals were scored. If it is still tied after extra-time thats when you have penalty kicks. Each team takes 5 kicks. If its still tied after that, its sudden death. So if you score and your opponent then misses you win.
Hope this sheds some light on the subject. USA had a great tournament getting to the quarter-finals and were the better team vs the Germans. They should have an even better team in 2006 but the traditional teams of Brazil, Argentina and the European giants will be very hard to beat on European soil.
Maybe if the USA gets the WC again in 2014 they would have a decent chance of winning.