There is no specific code for stuff. The right question here is how do programmers achieve this(now I'm sure morpha will pop out from somewhere and correct my correction, but anyway, back to the point).
For speed fines and auto-penalty-clearance you would use 2 events.
1: When users leave the pit lane.
2: When users receive a penalty.
Those 2 would be the most appropriate ones.
For 1: When a user leaves the pit lane, all you have to do is send a server command "/p_clear [username.goes.here]". That way penalties will be cleared a few moments after the users cross the pitlane from the inside->out.
2: When a user gets a drive through penalty, that means that he has been going 80+kph in the pitlane. Stop-go means 90+. Based on this information you can set your fines, inform the user and deduct cash appropriately for your application.
Since you're using LFS_External as a base, I can give you even more detailed information, but I haven't used C# in a long time, so I can't speak by heart now. But anyway, this should be enough to get you started, imo. Or at least I hope so.
[E]: I forgot that you even asked about spectating AIs. Well, I haven't done that myself, since I didn't consider it so crucial. I just felt like mentioning that I can't help you here unless I fire up C# and do some experimenting myself, but I'll have to disappoint you here - I'm busy with other stuff right now. =/
