I'd like some information on the details of how and where torpedoes were stowed on the various U-Boat types. I'm curious about how this changed through various times in the war as well.

I see the Type-II listed here with only a pair of reloads, however I recall "Aces of the Deep" (A rather detailed & realistic U-Boat sim, for the time) portraying the Type-IIs as having three spares? Is two spares considered "Normal" with a third being an occasional thing, or is it simply an error?

I'm already somewhat familiar with the Type-VII's setup of six spares forward, a single spare aft, and one torpedo in a stowage cylinder fore and aft outside the hull. I understand that later in the war the external reload tubes were often left empty as they were difficult to utilize when you were under constant air attack.
-Did the addition of the schnorchel force the removal of either external reload?
-Did the boats ever carry extra torpedoes internally to compensate for this?
-I've been told, but I take it as a rumor, that it was somewhat common to carry TWO spare torpedoes in the aft room instead of just one, is there any truth to this?
-Where was the VIIC/42 to have carried the additional two torpedoes?

The Type-IX series confuses me the most, however...
-Why does the IX carry only four spares up front when the smaller VII carries six?
-Did the installation of the schnorchel force the removal of any of the external torpedo containers?
-Did the Type-IXs ever carry additional torpedoes internally fore or aft to compensate for the inability to retrieve the external spares?
-Were the external containers left empty later on like the VII's, or did they continue attempting to use them?
-Where did the IXD carry the extra torpedoes?

Finally, for all of the boats with external stowage, what type of torpedo was most common for external stowage? I recall that "Aces of the Deep" depicted ONLY T-1/G7a steam torpedoes in external stowage at any/all times of the war. I would imagine that battery powered torpedoes might be problematic if they were in an area that made them hard to maintain?

Thanks in advance for the answers, and sorry for the big complicated question!