Xcode has a habit of putting all kinds of (redundant) information at the top of each code file it creates, containing copyright notices, class names, project names and client na
There may be a way to update your comments but it will be tricky.
As far a customizing the template, this is not as bad. it is just a text file located in
/Developer/Platforms/iPhoneOS.platform/Developer/Library/Xcode/Templates/File Templates/Cocoa Touch/
Don't edit the files here, they will get overwritten when you update, or reinstall xcode. Place your custom templates here, in your home directory.
~/Library/Developer/Xcode/Templates/File Templates/
High Order Bit explains further.