1 - the ATC tell the pilot to maintain the minimum speed or tell him high speed is approved then the pilot will know that to keep distance from other aircraft he gotta maintain high speed
but in some situation the ATC could tell the pilot a speed
2 - the center handle the aircraft in two situation ,, first if it is out of the approach controller range or higher than the transition altitude of the area so when the aircraft inbound reach the approach range the center control well transfer it ,, however if it reached the approach controller range but high than the transition level it will keep contacting the center control until it reach the transition level of the area so the center will give the aircraft radar vector until it reach the approach Range it will be transferred to the approach controller and he will continue the radar vector until the establish then transfer it to tower ,, but usually the center controller give the aircraft only the altitude until it reach the approach and then the approach will give it the radar vector and the altitude , because the approach have about 25 NM so this is enough for the aircraft to be vectored perfectly to the ILS with no problems
3 - the flight simulator X ,, i saw some books about the flight simulator X in Switzerland it was in french ,, it explain everything for you
the atc press (( ` )) this button located usually on the left of button (( 1 ))
you gotta connect at the ground to the ground controller then ask him for clearance to taxi to active runway ,, then he will give you ,, continue taxi on the taxi ways he gave you until you reach the runway then contact the tower (( you will see the frequnsies on the atc window and contect them by pressing the numbers on the left side of the controller name )) so when you reach the runway conatct the tower take the clearance for take-off then take-off ,, if you have filled a flight plan using flight planner in FS then you will be handle to the approch then the center to continue your flight
if not you will continue your flight on your own
+ there is a website called IVAO
link : www.ivao.aero
its nice website you can talk to atc ,, you not pressing button and they will answer you etc
and there is event ,, you will be handled to atc and many useful things
(( you connect using flight simulator (( any version you like ) and see other aircraft taxing , roling on the runway , and even in the air while they are flying to their destinations ))
any more information you can email me from my profile ,, goodbye