Yes, it is as official as any other.
It is unknown, the Eighth Doctor only appeared in a movie.
The Daleks appeared mostly in the first and second doctor's era. If you count "The Dlek's Master Plan" and "Mission to the Unknown" as separate stories, they have appeared in 14 stories.
There are currently no official announcements regarding Martha Jones returning to Doctor Who. However, previous companions have made surprise returns in the past, so it is not entirely out of the realm of possibility.
It has already been released on the official BBC website, if you are talking about Doctor Who: The Adventure Games.
At the moment it is unknown, but it will probably say during the sneak peak at the end of the Christmas episode. The impossible astronaut is the first episode and the second is Day of the moon :)
You can watch them for free on the BBC's official replay website - BBC iPlayer.
Doctor Who: The Adventure Games is an episodic third person game based on the Doctor Who TV series. Each episode is available as a free download only for UK residents. They can be downloaded from the official Doctor Who website.
The only Classic Doctor Who episode in which the Doctor had no companion is 'The Deadly Assassin'
The Doctor's Daughter was first, it is episode six of series four, Silence in the Library is episode eight.
According to a survey of Doctor Who fans the most popular Doctor Who episode was The End Of Time.
The weeping angels appeared in the doctor who episode Blink episode 10 of series 3 doctor who
"Blink". It is my FAVORITE Doctor Who episode and it's REALLY freaky.