Body,
To get the most gold out of your allies, you need to at least have whatever your next land costs in allies, maybe more. You can test this by buying smaller allies and hitting an eb until you see that the allies bonus doesn't increase anymore
How do you link your pc account to your Iphone. I know there used to be a button on the top for it but I've started playing this game again after a long time and it's not there.
Stats that do not move as your troops and spies go down. For example, as your troops go down attacking an EB, you do less damage (supposedly), however, static stats like equipment would stay as powerful.