1) Admin side. Add files tab. http://postimage.org/image/hv3u50zjl/ It allows you to select files not from computer only, but from already uploaded files too (from server).
2) This is related. http://postimage.org/image/rd0najnth/ This function allows you to duplicate selected file on server. The function will change duplicated file's name by adding [1] or [2] in the end... If function is turn off, the page or product will use the same file that probably are related with other pages. After you delete it, the files will disapear from all pages.
3) If parent page has specified template or theme, all new or updated subpages will have the same template or theme too. You will not need to set it sparately for each of subpages.
