I'm loving this series. As a long time Doctor Who fan it's always fun to hear people's reactions to the early years, particularly seeing them in order.
To expand upon the answers to 2 questions that Mike asked about the TARDIS. We have seen TARDIS's in their natural state, without the chameleon circuit activated. In one story (I won't name it because it would ruin the surprise when you get that story, but i think anyone who has seen it will know which one i mean), where we see a number of TARDIS's in use, mainly by one particular character but also towards the end we see more on Gallifrey. They appear to be plain black cubes, with a door that slides out.
Also in reference to the question about whether the TARDIS takes on the properties of objects it disguises itself as, the evidence in the series seems to suggest that it does. In a Sixth Doctor story, the chameleon circuit starts working and at one point it disguises the TARDIS as a fully functioning organ, and the Doctor plays a short tune on it. But more notably, in a Third Doctor story, the Master's TARDIS (admitedly a more advanced design) is disguised as a spaceship, and works like a functioning spaceship, flying onto the planet and landing.