The following list includes suitable secure FTP capable programmes:
Mac OS X: Cyberduck
This depends on your expected amount of data. You can at anytime purchase additional storage.
Of course, your data is accessible worldwide.
Yes, for this we offer Online Backup.
You can change the behaviour of Konquerer in the menu:
Tools -> Select Remote Charset -> Unicode (utf8)
Please download the following update from the Microsoft Website and install it: Software Update for Web Folders (KB907306)