Iran Military Forum

Hello to all and greetings from Bulgaria.
I hope this is the right place to post my question.

I have to write a report about ancient persian political and military system but the information i`ve already found online is not enough, so I thought maybe you could help me.

I`m interested in general how the kind of Persia was called, I`ve found shah, padishah and many others, which I find confusing. What is the difference between them or they are just the same name for one thing. Are they any ministers, magistrates, local governers, mayors, etc. and what role each one of them played in ruling the empire ?
What was the military structure? How were called generals and other beneath them ?
How was involved the religion in public life, did the priests had any role in making the rules and any authonomus power ?

I`ll be glad if you give me the general info and maybe point me to some more detailed resources.
Thank you in advance and wish you all the best !

One online source I find quite interesting for quick surveys of Iran's history, would be www.iranchamber.com.

They have articles on Iran's Achaemenid empire in general, as well as some of its military aspects. For example: 
http://www.iranchamber.com/history/achaemenids/achaemenids.php
http://www.iranchamber.com/history/achaemenids/immortals.php

You should also try the Encyclopedia Iranica under http://www.iranicaonline.org/ , there are useful bibliographic references at the end of each article.

Hope this helps.