Formula 1 racing question

[BENZ-LGB]

Sunday my son and I were watching the Canadian leg of the F1 cahmpionship series.

BTW, Mercedes-Benz won. Yeah!

I know as much about F1 racing as I know about hockey--ZERO, ZILCH, NADA!

While watching the race we noticed that every time that the yellow flag was waved, adn the "safety car" came out all the racers would hold their position in the lineup--which I guess is a standard rule (not to take advantage of a yellow flag).

All (or most) of the racing cars, while following the safety car, would weave from side to side (like you see highway patrol cars do when they are trying to hold back traffic).

If they cannot move ahead of another car during the yellow flag, wha tis the purpose of the weaving? Keep tires warm (and soft) perhaps?

The race was very exciting, lots of wipe outs. The Benz team is doing exceedingly well, far ahead of Ferrari and BMW in the overall standings.

Also, can someone explain to me some of the F1 rules, like when it is proper to make a pit stop? A Ferrari got the black flag for going into the pit (when it couldn't) and was forced out of the race.