1. Good on you for setting your ambitions high. From what I've seen, most people who get into Cambridge for Medicine have a string of mainly As and A*s at GCSE, followed by mainly As at AS Level and A Level.
2. No medical school is better than the another one. They all offer degrees which are accredited by the GMC.
3. Tuition fees for 2009 entry are £3,149, I think. However, with the uncapped fees coming into place for 2010 entry God knows how high they'll be.
4. Pretty much the same as the skills as you require at A Level, I presume.
5. I don't know, I'm not a medic!
I hope this helps in some way.