The minimum requirements can change from version to version and are checked by both the AdminCP support tool as well as the install and upgrade process themselves.
As for permissions, some servers require writable folders and files to be 0777, while others require 0755. That is why the answer is evasive - if you are hosting the software on your own servers, the required permissions can vary depending upon the server configuration (whether you use suphp, as well as what user/group your FTP vs webserver user runs under, among other things).