The airplane is not going "really fast" it is more or less in slow flight. An Airplane has to be below a certain speed to land, but also can fly slower than it takes to take off, so in fact you are just noticing the speed of it. In comparison to normal flight it is slow, in comparison to takeoff it 'can' be slower.
The flaps move downward, the landing flaps anyway. The speed brakes flap up to slow the momentum of the airplane more vigorously than the landing flaps. Landing flaps are also used on takeoff if a shorter runway roll is needed in the case of obstacles at the end of the runway or a shorter runway. The speed brakes are automatic and are deployed when the wheels touch down but can also be deployed manually.
All modern international jets are equipped with a GPS, the airplane also has other equipment that can actually be programmed to fly the flight automatically, meaning takeoff (TOGA) or Takeoff/Go Around, follow flight path to destination, and can even be used to land which I will describe that process at the end.
The runway they are going to land at has a special number assigned to it based on the degree deviation clockwise from 0 or in other words 360 degrees. It the airplane is landing south the runway would be called runway 18 or "one-eight". These numbers are reversed as in 18 is north on the airport and 36 (three-six) is south, so if the airplane is heading towards north he sees 36 if you know what I mean. If the number 36 was on the north side of the airport then when the airplane landed south he would see 36 which is north instead of 18 which is south. The opposite ends of the runway is marked differently with different degree numbers. The pilot enters these number into the computer as it will give him the best GS or glideslope (up and down) and the best localizer (Left and right).
The landing I was telling you about using the autopilot is called an ILS or Instrument Landing System landing used in what is called IFR or Instrument Flight Rules conditions, or when viability is not possible out of the cockpit. ILS landings are categorized in three category CAT I, CAT II, and CAT III, CAT being category. A CAT III ILS approach is when you have zero visibility out of the cockpit. How this is done is the pilot of course get clearance from the tower, sometimes accompanied by directions to the airport based on needed circumstances. The pilot used the number of the runway and looks for a special frequency designated to that runway and punches it into the NAV radio and verifies he has the right runway by a numerical Morse code played from the NAV when he punches it in. At that point the pilot makes sure he is centered with the runway using the localizer, than he waits for his spot on the glideslope to center and then hits a button sometimes referred to as Auto Pilot Procedure button, when that happens the airplane takes control and starts to descend towards the runway, keeping the glideslope and localizer centered itself. When the airport passes certain markers, outer, middle, and inner, it plays certain sounds notifying the distance from the runway. When the airplane gets closer to the runway the airplane plays the "minimums" or the feet from the runway and counts down to at least 10 until the airplane touches down. The minimums are not only ILS but manual landings too.
Reverse thrusters are when the engines actually blow air out the front for extra stopping power, just though I'd throw that in there.