AWS IAM user creation and access

IAM user set up can be found here:
http://docs.aws.amazon.com/IAM/latest/UserGuide/Using_SettingUpUser.html

Give them 'Power User' if they need to create instances and fully utilize AWS services.

They will use a different URL (not aws.amazon.com) then you use to access your account.  More here:
http://docs.aws.amazon.com/IAM/latest/UserGuide/WhatUsersNeedToKnow.html