How to correctly create a test installation as a copy of the live site

[Gnuru]

I would like to create a copy of the live site as a test installation. How do I correctly do that?

Currently I copy all the files to a new location (where the subdomain test.xxxx.de points to) and create a copy of the database. I then change the settings in conf_global.php to change the db-name and the cookie prefix in constants.php.

What does not work is, that all the images and css don't work until I adjust the file path settings in admin cp for datastorage.

But if I do so, IPS will move all the files away from the live forum :-(

How do I correctly do that and make sure the test installation does not:

• send emails (but do save emails to file)
• move any files to the test installation when changing path in admin cp
• use another cookie