To manually do updates
apt-get update is used to resynchronize the package index files from their sources...
apt-get upgrade is used to install the newest versions of all packages currently installed on the system from the sources enumerated in /etc/apt/sources.list.
apt-get dist-upgrade: in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages; apt-get has a "smart" conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important ones if necessary.
apt-get nor aptitude will update manually installed software. What you're most likely to have to do is use dpkg with an updated package, or using dpkg with the --update-avail <Packages-file> option might work (it *should* if your packages came with update infos).
To restart network interface
sudo /etc/init.d/networking restart