Yes, Formula One refers to itself as the world championship.
Can you provide any additional context? Is it a dated document? I ask because at this moment, two races have been run in this year’s season 19-race season. (The third is this Sunday, in Bahrain.) Last year there were 18 races. 2003 was the last 16-race season.
There are no “periods” per se in F1 racing. You might speak of the first or second half of the season, but “period” is not a standard term in the sport.
“15 wins out of 16 races” correctly characterizes the Ferrari team’s position after the first 16 races last year: Michael Schumacher and his teammate Reubens Barrichello had won all but one of them. And at the end of the season Ferrari had won 16 of 18; 14 for Schumacher and 2 for Barrichello.