Filepath upload

Hi All
I would like to change the file upload path for storage of static files.

I have a site with the default upload path and my service provider suggests a better frontend performence by changing the static files storeage place.

A have made a “files.xxx.dk” domain for the purpose.

1. A have hear that the .htacess file has to changed – how?
2. And the filepath setting in the super admin part – where?
3. Have wil it work with the old files on xxx.dk domain?
4. And should I move all the old files?
5. will it work with cache plugins like “w3 Total cache”?

Best,
Jesper