Can I move files and submissions to my hard drive or Dropbox?

can i save or move files to hard drive or Dropbox? what is the maximum number of JPEGs that can be attached to submission form?

You can integrate your form to Dropbox: https://www.jotform.com/help/77-Upload-to-Dropbox-with-JotForm. 

You can upload up to 1GB of files for the single file upload field. To know more about the limits, please check this guide: https://www.jotform.com/help/33-Changing-the-File-Upload-Size-Limit.