Hidden files and Dropbox

I share photos with others using Dropbox. I send an email telling the sharees, the total size and number of files. I realize that different computers might report a different size due to different block sizes, but the share often gives a different number of files as well. That is, the Windows-reported number of files in the Dropbox share on my computer is larger than the the number shared. By occasional actual count if visible files, all files are shared, so I’m assuming Dropbox does not share some kind of hidden files like perhaps thumbnails.

Is there a way to show the hidden files in just one directory? I know how to do it for all directories using Control panel, and I’m pretty sure I used to know how to do this in Windows XP, but I can’t any more.

What type of hidden files should I not delete? I think it will mostly be thumbnails, which I have safely removed in the past.