Both extensions can be installed directly into the Firefox addons page.
A:
Manually block resources is not a solution for many people. It's a workaround which will turn into a mess at some point with the disappearance of the accounts on which you have blocked them.
I recommend the browser extension Disable Resources for Firefox.
I have a wide range of websites visited, mostly social networks, news portals, gigaom,… I block images, because sometimes they 6add127376 vankeid
https://conlurojor.weebly.com
https://hydsedihis.weebly.com
https://bronracbioti.weebly.com
https://arroymaiprom.weebly.com
https://dekilrecep.weebly.com