[DarkFish]

I'll try to help you a bit here

Originally Posted by Sheldon

1. Patches - Here in the SubSim site I see an official 1.4 patch but in the forum posts I have seen reference to a 1.5 patch. The 1.4 patch instructions say to uninstall then re-install then apply the patch. That's kind of a pain. Is that really necessary? What happens if I have already started a campaign?

1.5 is the U-Boat addon. It adds the option to play on the German side, and fixes a few bugs as well. You must buy it however, I just checked and it is only $9,95 on Direct2Drive.
for a DVD you can best search on sites like ebay.
I think uninstalling is only needed if you installed any mods, as in that case it could cause CTD issues if you install the newer version. If you're playing vanilla it shouldn't be a problem
If you already started a campaign it'll probably become corrupted, unless you are in port.

2. Widescreen - I recently bought a 24" widescreen with a native 1920 x 1080 and have searched for a method to make SH3 and SH4 look good but the games just display stretched wide. My solution is ... to just use my old monitor when sub simming. Is there a better option?

I don't know about this as I ain't got a widescreen monitor, but AFAIK it should be possible. Maybe if you do a search here?

3. Salvo - I cannot for the life of me figure out how to fire a salvo. The 'S' button on the tube selection panel doesn't seem to do it.

There's no salvo function on fleet boats. Just launch a few torpedoes in close succession. But remember to first turn the spread angle dial around a bit prior to every launch as all torpedoes will travel on the same course if you don't.

4. First Sub - Any recommendations for what type of sub I should captain?

just as on the German side each boat has its own up and downs. The gatos and balaos are the most modern ones and can dive deepest. The S-class is comparable to a Typ II U-Boot, small, slow, not carrying too many torpedoes and with a shallow max depth.
Just choose a boat you like.

5. Function Keys - It seems like most of the F key functions are still there ... they've just been re-assigned to other F keys. Why would they do that?

you ask me?

6. Running Depth - Am I just being paranoid or will aircraft/ships spot me at periscope depth?

They will, though I'm not sure if they will in stock game. It differs with every supermod, but on my RFB+OM install I just got blasted while sailing at periscope depth.

7. Targets - There seems to be fewer big merchants and more military targets and smaller transports. Is that about right?

I don't know about the ratio, but there are unrealistically many targets in stock game. RSRDC fixes this.

8. Local Time - My clock seems to be broken. I am cruising off Hokkaido and the sub's clock says it is 14:00 local time (2 pm) yet it looks more like 2 am ... pitch black with a starry sky? Do I misunderstand what local time means? It seems like my clock is off by 12 hours.

AFAIK the clock shows base time instead of local time.

Any other advice for transitioning from SH3 to SH4?

1st play around a bit to get the hang of SH4 and then install one of the supermods (TMO/RFB/FOTRS, just take a look at the fleet boat mods forum) and install RSRDC which completely overwrites the stock campaign and changes the shipping to historical values and routes.
I hope this helped you