Usually the downloader you need depends on the website you want to download the images form. In general, here are some opensource ones which support a variety of websites: gallery-dl, ripme and various other ones on github. There for paid ones, there are Extreme Picture Finder and Bulk Image Downloader, which have easier to use GUIs and are properly maintained, but as said, they are paid. Source: about 3 years ago

Yeah, I found bulkimagedownloader ages ago but its not a free tool. Not sure of what limitations the trial have. Source: about 3 years ago

If you use a solid host like WPengine and a security app like wordfence.com it would be a very rare day indeed to get hacked. Source: about 1 year ago

If on wordpress, use the free version of wordfence.com to scan your site and identify possible viruses. Continue to use wordfence to protect the site, and if a successful business blossoms, consider the premium paid version. I'm not affiliated in any way, I've simply used the product with success for a number of years. Source: about 2 years ago

You can also read the documentation to learn about Wordfence's blocking tools, or visit wordfence.com to learn more about Wordfence. Source: over 2 years ago