Almost. The 90 minutes doesn't include the half time break - there are two halves of 45 minutes. Just before the end of each half the number of minutes added on for injury are announced, but the referee won't stop play dead on that time - he will wait for a natural break in the game - like the ball going off the pitch.
The size of the goals was set years ago when goalkeepers were about 6 inches shorter than they are today. That's why the scorelines tend to be fairly small. Back in the day half time was a chance for the players to have a cigarette and a pint of beer. Don't think they do that any more...