Temp is just something to derate the engines.
V1 decreses because you will achive VR further down the RWY than you would have if you had been using TKOF thrust, hence giving less distance to stop on.
Concerning the NAP, PANS-OPS standard proc A stipulates that you should climb with TKOF power to 1500FT and than use climb power. I suppose that this is something ICAO has thought to be the least noisy proc for the largest group of aircrafts.
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Está esto el cambio de marchas?