1.Brahmins pens are blocked by developers fro now, will be fixed in next update.
2. You can get some basic SG from VCpatrol vs Slavers encounters below Vault city etc, but do not loot corpses before patrols do, also take care to not come too close to them
3.Armor class is applied only while running in RT, in TB you have to spend certain number of AP for move to be applied.
4. every build depends on what it will be used for, PVP cripplers,snipees might use SG, just search forum or wiki for some builds. Idk about HtH sorry
5.You have to tag frend and stand close to exit grid where he leaves map.Tag is done by holding left clock on player, then release hodl on icon with characters and arrow.