Here is a calculator to help you find out the total value of allies u need to be at max ally bonus. http://kawtips.com/mpcalc.php **Note 1. This is 99% Correct. Probably as close as you can get to finding it.
Re: Max Plunder I put in my attack and defense bonus to allies as 66720 and 66720. It said I need 733,920,000 I'm 99% sure this is wrong.
Re: Max Plunder Yes. This is wrong. You are not taking into account the effect of guilds or SOSs or vols. I'm not sure what you are taking into account. If you're using the 5500 thumb rule...that's just a thumb rule.
Re: Max Plunder You don't hire allies to maximize the plunder. Rather to maximize your allies bonus. And that depends on each building you have.