You might want to post over in the linux subforum but I will answer these
sudo (superuser-do) is the command to run commands with escalated privileges
To get partition info(-l means list):
sudo fdisk -l
gddrescue is not installed by default, just grab it from the repository.
sudo apt-get install gddrescue
gddrescue will be in the 'universe' repository, you will need to add it to your repo list. (instructions on this page)https://help.ubuntu.com/community/Repositories/Ubuntu
or if you want you can compile it from source http://ftp.gnu.org/gnu/ddrescue/