Trisquel 8 preloaded software

> where (link) can I find the list of preloaded software of Trisquel 8?

The most reliable way to see what software is already installed on your
system is to open Synaptic Package Manager. This will show you every
package installed and allow you to add/remove packages.

You can also go to Add/Remove Applications for a more simplified list
of programs that only includes graphical applications and excludes
things like libraries, but this list will not be as complete as that in
Synaptic.

> This to avoid downloading a software once again, if this software is
> already installed in the new Trisquel 8 version.

This isn't really something to worry about when installing software from
the Trisquel repository. If the package is already installed, the
package manager will just upgrade the package if there is an upgrade
available, or it will do nothing if there is no upgrade available.

I recommend reading this page

https://trisquel.info/en/wiki/how-software-installation-trisquel-different-windows

for some general information on how package management works in
Trisquel, and reading this page

https://trisquel.info/en/wiki/installing-updating-and-removing-software

for a guide on how to use Synaptic Package Manager and Add/Remove
Applications.

> New in town

Welcome. :)