Neil Gaiman on WhoSay
I didn't know this
One of the callouts from Doctor Who fans has been why the swimming pool in the Tardis wasn't shown in The Doctor's Wife?
It wasn't budgetary reasons, or stinginess by the producers
Karen Gillan can't swim.
Making television - and especially making Doctor Who, where you have to imagine a new world (in my case a new universe) with every episode - is always a negotiation between dream and reality. (That was the same email in which I learned that we weren't going to have the scene in the Tardis Swimming Pool because Karen Gillan couldn't swim
Also, about the erasing of Tennant's control room:
Of course it exists. The TARDIS keeps it archived. House deleted it, but I have no doubt that, once they were in a place where that could happen, the TARDIS undeleted it, tidied it up and put it somewhere out of the way, along with the other things she keeps close to her chest.