Should I run 'apt-get autoremove' to remove the above packages that are no longer required?
Every piece of software that you have installed is a potential security hole.
The packages in that list were installed in the past as dependencies of some other software you installed. Later you removed this software but the dependencies remain there. Probably you aren't using those, so it's safe to remove them.
blocknotify is now working!!
Glad to hear that!
$ dpkg -L dh-apparmor
/.
/usr
/usr/bin
/usr/bin/dh_apparmor
[...]
dh-apparmor is a tool for debian developers ("dh" = "debian helper") and has nothing to do with the actual execution of apparmor.