Cleaning an html webpage: delete old (unused) and add new files

I need someone doing a little job: I will provide ftp access to a webpage.
Given:
* minimalistic html webpage with 3 pages
* a bunch of picture files (and subfolders) not displayed in the webpage
* old files (images) not displayed on the webpage

Wanted:
* delete all image files that are not displayed on the html code
* delete all files which I provide as file (compare file names and delete in the html code)
* fill the table frame in html with new, given photo files
* beforehand: resize the new images to 500 px long edge