Permanently switched to Trisquel, have a few questions ...

You may use Scriptish (https://en.wikipedia.org/wiki/Scriptish) instead of Greasemonkey. I use it and is very good. Scriptish is a fork of Greasemonkey.

Abrowser's addon database works like a wiki. If something's missing from there, you can add it.

On the right side of the trisquel's page you can see a list. In that list click on "create content" for your addon submitions. Remember that those must be really free not "almost". Those addons must be under a free license and open source.

About the "block reported attack sites" and "block reported web forgeries" disabled, I'd like to mention that not all of them are really what authorities say. When you are not allowed to view a site is not always for a good reason as there are reasons like goverments don't want people to know something. An example are revisionists blocked sites.

'And lastly, why are "block reported attack sites" and "block reported web forgeries" disabled by default inside Abrowser?'

As far as I know, Abrowser would have to query a server if a site to be visited is a reported attack site or a forgery, which would reveal your browsing habits to the server.