@johnnycat
Hi Cat
Glad you enjoying your trip. Minus the train ride 
Fctrys and Subs work basically the same as the OOB rules
https://www.hasbro.com/common/documents/60D52426B94D40B98A9E78EE4DD8BF94/6B7BC7B257E049558181A7D71B822DCF.pdf
https://www.hasbro.com/common/documents/60D52426B94D40B98A9E78EE4DD8BF94/01976084F8F14994BE3DA27CAF498033.pdf
(special Global Rules at bottom of rulebooks)
with a couple exceptions. Original Fctrys at Game Start can be upgraded by the Original Owner to "Heavy Industry" . Page 27 of the Captain's rulebook
https://drive.google.com/file/d/1jI_1JdIC-1KiTihBICJAbtX3GpVYnNgf/view?pli=1
Basically, for 2 PUs you can update a Minor Fctry so it can now produce "4" instead of "3" units per turn.
A Major Fctry costs 3 PUs to upgrade and can produce up to 12 units per turn instead of 10.
So, your Egypt Fctry can only produce 3 units. Same as OOB and yes it is a common build in OOB as well as EXP or HRE, HouseRulesExpansion.
The S Africa Fctry can be upgraded and then produce up to 4 units per turn.
Submarines can be ignored by other Naval Vessels unless it is an unescorted Transport. This is the same as the OOB rules and triplea does it correctly.
The biggest difference are the German U-boats. Page 41 of the Captain's rulebook. Basically, they only cost 4 PUs instead of 6 and if there are 3 or more present, they will form a "Wolfpack" and all U-boats will Attack or Defend at "3" for the first rd of combat only.
Edit
Ftrs and Infantry are your best bet to defend against Sealion. See the "Home Defense Rule" page 38
Edit 2
Subs aren't that effective by themselves in a defensive role. They are better off part of a larger Fleet where you can use them to strike offensively. Either in combat or Convoy raiding.
You can dl some saved games from the "Play By Forum" thread that Panzer and Trout and I have played. Look through "History" to show each turn and how it played out.
You can also read some of the "Game Reports" at the A&A site here
https://www.axisandallies.org/forums/topic/37723/global-1940-1943-expansions-game-reports
and the Captain's "Strategy Guide" is here
https://www.axisandallies.org/forums/topic/37458/strategy-guide-global-1940
Edit 3

Wow ! What a Badass looking Mountain ! Might be a little sketch climbing it this time of year
Probably have to overnight it. I guess it depends what elevation you start at. Still, can't be a whole lot of daylight right now.
Use Caution

Edit 4

Beyond my paygrade


That looks more like a Expedition lol