New Guy, quick question

[HeyThere]

Hello Everyone, I registered today after I watched a Youtube by Idjester on Antietam.  The ACW Tiller gaming system looks incredible.  I wanted to buy and invest my time in the Gettysburg Campaign.  

In Idjester's Youtube video (Civil War Battles ANTIETAM John Tiller Software Let's Look At this Game Scenarios, Counters, Maps - YouTube) at 45:51 he is reading "notes.pdf" file within Antietam.  It lists a bunch of changes that appear to be the way things should be.  

That video is over 2 years old and at that time, GBurg did not share in any of these "new updates."  I just checked the Tiller site and I see the MAP UPDATES now exist for GBurg, which they did not when this video was made.  My question is, do the changes in the Antietam "notes.pdf" document from 2 years ago now carry over into the Gettysburg Campaign rule set?  I was hoping they did.  If they did not, I will buy Antietam.

Are there any rules differences between Antietam and GBurg, or all Tiller ACW have the same rules? 

I want to spend some solo time with AI before looking for PBEM.  While playing against AI, I was wondering if PBEM people use 'Extreme FOW' in PBEM?  Until I start playing, I am not 100% sure I understand all of it, but that sounds like that option is a drastic change to the game.  To me (with zero experience), it sounds like this would be the best way to play.  But if PBEM people do not use it, I guess I will not practice with it.  Any info or comments on 'Extreme FOW' play is greatly appreciated.

Thank you again for allowing me to be a member of this forum.