The first championship race was held in 1950 at Silverstone. This was not the first race held to be held under (International) Formula 1 rules technically but it was the first world championship race.
A modern Formula One car is a single-seat, open cockpit, open wheel race car with substantial front and rear wings, and engine positioned behind the driver. The regulations governing the cars are...
This is simply a matter of opinion, but I would say the the season opener, in this year's case Melbourne, the season finale, in this year's case Sao Paulo, and possibly Monte Carlo.