Seeing as most of the questions have been answered thoroughly, I thought that I would add to a couple.
6. As mentioned all drivers are provided with two types of dry tires, both of which must be used in a dry race. If a team at any point in a race uses intermediate or full wet tires, they do not have to use both tire compounds.
7. The drivers microphone is imbedded in the fireproof balaclava that the drivers are wearing and is placed on the drivers lips. The microphone that records the engine sounds are, as far as i know, placed in the T-bar you can see on top if the car. It is isolated from wind noise, but there does not seem to be any specifications available.
8. If it is deemed that a driver might have gained an advantage by leaving the track, it could be by overtaking as Massa did in the Hungarian GP, the drivers often let the other driver pass again to avoid a penalty. If a driver has multiple offences of leaving the track, they usually receive a warning, and if they continue to leave the track they will most likely get a penalty.
9. Red Bull often have problems with their KERS system, especially in warm weather such as in the Hungarian GP. the fail 22 message was likely a request to the drivers to stop using their KERS to prevent overheating and damaging the car. If you watch more races you will likely notice that Mark Webber have mechanical defects more often than Sebastian Vettel, specifically Marks KERS often fails. This is probably because Mark is somewhat taller than Sebastian, and the engine compartment of the Red Bull is already pushed as far as possible thermally in Sebastians car. For example, Red Bull only use about 75% of the 80 extra horsepower that KERS allows.