Sorry to bring this topic into the land of fantasy but...
What happens if someone on my team is disqualified for doping? Are all his points forfeited? Will all the placings behind him be recalculated?
If he's DQed during a stage race then his points will be zeroed for the race, ie all the stages.
once a race (one day or stage) is complete, the scores stand and subsequent doping busts won't change them.
a DQ doesn't have to just be for doping: renshaw was DQed from the tour last year for fighting and a lot of teams lost a lot of points