Torpedos: G7a T1 or G7e T2 ?

[anthrax]

I would like to ask the veterns which torpedo do they prefer to use?

The G7a T1 which has high speed but leaves a bubbly wake or the slower G7e T2 which is wake less?

1.) Can enemies detect wakeless electric torpedos fired at them?
2.) Which type of torps do you use for the the following scenarios?
a. Ambushing a convoy escort at 11 knts , 0.5 to 1KM range? day time
b. Ambushing a convoy ship ? at 9 knts , 0.5 to 1KM range? daytime
c. Ambushing high value warship @ 20 knts , 0.5 to 1KM range? daytime
d. Ambushing high value warship @ 20 knts , 2 to 3 KM range ? daytime