This will only affect your personal files if you do a custom reinstall. If you are just reinstalling over existing without doing the custom install it will overwirte your windows system files and any files you have in the system directories. (i.e. C:\windows, c:\program files etc..) Your documents, videos, music, and pictures will be in a directory marked .old or since profiles are still intact to the users directory they will still reside there.. I would recommend investing into either OneDrive, GoogleDrive, or Dropbox to effectively backup what you're trying to save to provide some backup of your files.
I can do the saving of the files and start the reinstall remotely however you will need to monitor at certain points as it will cut my connection and then reestablish if it can in process. Overall what are you trying to achieve? Is there an issue with the current OS? I would need to reinstall if we can initially find out what's going on with the current. I would charge $45.00 to review and if we cannot fix I can provide the additional charges if required. The $45 would be applied to the additional if required.
live chat using which software? If you're using some sort of live chat software you're using the same connection which would be just as expensive. We have our own remote software for this type of service.