In order to redirect to HTTPS, add an .htaccess file to your website root with a redirect directive.
Tidy, aka cruftless links, are good for all aspects of website design.
It is possible to customise the lightbox libraries with CSS. Therefore, use following custom CSS code on the Stacks page.
Disabling the right mouse click and with this the appearance of the context menu (which leads to a direct download option for photos) will not prevent anybody from actually doing so.