Google Apps setup

Hi All,
Hoping someone can give me a few pointers please regarding the setup of Google apps, I've done a search but cannot seem to find what I'm looking for. I've been asked by one team of tutors to implement Google Apps for their course, and this will be the first instance of Google Apps in our institute. Where I'm stuck is how to start this off, as other courses and departments will probably want to use Google apps too so I am not sure how this will work. From what I gather, we can only have one instance of Google apps per domain name, so will the first department who use Google apps have overall control over it? Or can it be compartmentalised for different departments eg Computing, Engineering etc..
I would be the 'administrator' rather than the tutors. Also is the setup quite difficult?
Thanks in advance

You should find what you need to know here Google Apps Help

You'd sign up for your school, then fill in the form at Contact Us - Google Apps Help and wait for them to upgrade you to free education version

Then install google apps directory sync and password sync, force everyone to reset their AD password, sync the whole lot, including departments as organisations in gapps, and then if you wanted give people in certain orgs more rights.

Thanks guys, I shall have a look