1) In most situations, the active runway will be selected according to wind/weather and sometimes according to noice regulations. If there is light traffic or the departure airport has multiple runways, you may have a choice. Otherwise, no. The SID will depend on your flight plan, the runway of departure and any restrictions on type of aircraft or filed airway.
2) Visual separation other than on final, usually not. Visual approaches, usually yes but sometimes you will be vectored to the visual approach for spacing. The spacing behind traffic is not just for your benefit. It is also there to allow departures.
3) Lower than normal speed is at your discretion unless otherwise stated by ATC.
4) See 2.
5) Other than visual approaches when you take your own separation, absolutely not.