Welcome to the forum
As for your question you will get radio messages to proceed with hostilities against the USA for example. You will also get historic messages like the capture of german enigma codes
I play with SH3 commander and im perfectly capable of running GWX but I feel that the added relaism isnt for me. Can you run by me any smaller mods, mainly ambience mods, not ones that dramtically change up gameplay.
One last thing id say get Sh3 commander ASAP and put on randomised tonnage. This makes the game just a tad more realistic as all ships dont have a fixed tonnage amount.