1. As I recall UK Perf A, a runways clearway can only be extended up to a certain point. It can be worked-out on a graph thats provided when making these calculations. A simple way to remember this requirement is to think of a TO from R24/25 at LAX. The clearway over the Pacific is 6,800 nm!
2. Angle between airfoil chord-line and relative airflow = AoA.
Maintaining the same attitude (body-angle) while deploying hi-lift devices:
Flaps will increase the AoA because it makes the chord-line (line from edge of flap to leading-edge) longer (lift-coeff) and at a greater "apparant" angle to the relative airflow.
Reverse is true when retracting these devices.
3. (Isa Dev x 120) + QNE = DH
Ex: QNH 1009 at airfield 5,500 ft. OAT -1 deg C:
a) 5500 at 2deg/1000 = -11deg decrease.
15deg at SL - 11deg = +4deg ISA at 5,500ft
+4deg - -1 = -5deg deviation (colder than ISA).
b) winding altimeter up 1009 to 1013 = 4mb x 30 ft = increase by 120 ft. 5500 + 120 = PH 5,620ft
c) (-5 x 120) + 5,620 = -600 + 5620 = 5020 ft DH