Hi,
I'm not sure about the amount of depth charges the usual suspects carry but i remember there being mentioned that some destroyers or sub chasers had around 125 or so from a thread a long time back and i'm not sure if anybody has altered the amounts in any way.
As for the excellent TM... if you are running 1.7.5 your really going to have to be subtle when engaging convoys....
the AI has been well for the lack of a better word "tweaked

" see Ducimus's TM info for what he may have changed... needless to say you cant just motor in on a convoy or the escorts are gonna hear you, Planes can now also see you at periscope depth and will nail your ass if you dont keep an eye on em.
I would also learn where to put the torps, if you are usuing auto targetting this will put all your torps in the same spot, you will need to spread them out over the ship to increase the damage.
i'd advise you also add some of the excellent ROW additions by the late Leovampire and friends, this adds quite a lot of immersion to the graphical side of things great eye candy when you blow an ammo ship

.