Answers IMHO
1. Depends on the altitude you are being held to, if you are high, you bring back speed to reduce energy. A lot of airlines suggest min clean in the downwind which can be around 200-220kts
2. Situation Awareness and to allow you to understand how much energy you are going to have to lose. Track Miles is better, but rarely accurately given.
3. My preference, all I am looking for is the quickest circuit that allows me safely to get rid of my height and speed to configure for a stabilised approach. Don't care what shape it is.
4. Rule of thumb as taught to me by old timer. You can tell how competent an ATC system is by how soon you get your clearance. 3rd world clearances are late, incomplete and chaotic. Listen to LGW or LHR to hear how it should be done.