A couple of newbie gameplay questions

[Slizen]

I just got SH4, and It's great (apart from the annoying graphic bugs) I'm not a sub fan though, so I'm not really that familiar with how subs work and I could use some help.
Here's the questions:

1. I've noticed there is an option to choose if the torpedo shall go fast or slow, but what are the disadvantage/advantage of setting it to fast?

2. I know it might sound obvious, but why have do you have to manually (with Q) open the torpedo tubes before fireing? I've tried with and without opening and I can't seem to notice any difference. Is it because my realism setting is to low or am I missing something?

3. I'm being hunted by a few escort ships so I dive to around 80 meters, changes course, slows down etc. I still end up with a few escort ships circling above me. I go into free view, checks out the ships above me etc and suddenly I get the mission failed screen, reason: sub destroyed.
Alright, I died... but the thing is I didnt notice anything. I didnt see any depth charges getting thrown into the water, no explosions sounds/water splahses, no message telling me they have even dropped depth charges and not even a sound from my crew telling me we have been hit.

4. About navigation and patroll missions. When I've been crusing around a while I get a report about a convoy half a grid away heading my direction. I change course to intercept it but I never find it. This has happend alot of times, I havent even once succesfully intercepted a convoy , what am I doing wrong?
5. And about the navigation map tools. Do they actually provide you with some extra information if you use them correctly? Or are they just there for helping tracking ship movements when on a high realism setting?

6. This isnt really a gameplay question, but it still is really irretating.
I'm constantly hearing voices from different people in my crew saying random numbrs like: one, three, two, five, six, two, one....
First I thought they were saying something about my bearing or course but It feels kinda unlikely since they are saying that constantly, all the time.

[Killer-Carrot]

Im gona let someone more experienced answer all the questions except the last one.
Someone on the forum said, that the no-cd crack causes the random numbers bug
so just play with your DVD in drive

[Soviet_Sharpshooter]

1: The faster the torpedo, the shorter the range, but for fast torpedos the range is still over 1400m's or something like that, so its fine.

2: If you open it before hand, when you fire a torpedo it will shoot straight away instead of having to wait a few seconds which could make you miss a shot

3: You may have been suffering from flood damage, might of missed a depth charge, rammed into a mine, rammed into a rock i dont rly know

Theres also a bug in this game where you can take random damage, crew fatalaties at random times, it may have something to do with having battle station on to long... no one knows really.

4: The convoys change direction and speed alot to avoid being intercepted when they've been spotted. Try and get a idea for what port its heading to, and position yourself somewhere between the convoy sighted area, and its destination.

[Slizen]

Originally Posted by Soviet_Sharpshooter

3: You may have been suffering from flood damage, might of missed a depth charge, rammed into a mine, rammed into a rock i dont rly know

Theres also a bug in this game where you can take random damage, crew fatalaties at random times, it may have something to do with having battle station on to long... no one knows really.

Ah I see, well I had battle stations on, and on a multiplayer game last night same thing happend again. I was watching the crew management page and suddenly all departments went red, switched to the dmg control page and most of the sub's systems where red/yellow coloured. I didnt understand anything at first, and a few seconds later the mission failed screen popped up.