where are the TeTeX packages?

Hallo,

I've used MiKTeX for most of my TeX-life, but now that I erased windows from my
disk I switched to the debian tetex packages. 

I believe I installed all the relevant packages: tetex-base, tetex-extra, but I
still get errors trying to compile, because latex can't find: "textcomp" and
"eulervmsys". 

In MiKTeX I would call the package manager, look for the desired pack and have
it installed. I was wondering if tetex had such a tool. If not, how do you check
that a given package is installed? Knowing whether the package is available, and
especially where (since the docs should be somewhere around) is quite helpful.

Moreover, does anyone know if debian refreshes the package list after installing
something with apt-get? That is, let's say the packages I want come bundled in
tetex-extra, which I installed - do I need to run some command (texhash?) to get
them on the list?

Thanks in advance,

Renato