That isn't a big post, by any stretch of the imagination!
As to your actual questions, simply extracting files to /usr/local is just the same as unzipping under windows. You have the install what is within the tar.gz files. Usually the setps that follow are:
./configure (maybe some options)
(sudo/root) make install
You should read the INSTALL or README file in the top level directory (usr/local/whatever), and see if you need to do something else.
You won't need to change anything in the profile or path settings. Where you are extracting those files is fine, and the install process will most likely put the executable files in /usr/local/bin, which is in the path of nearly every user on the system. You may need to reconfigure a few things, but it should just work.
You do know that you don't have to install from source? It is fine to, but it takes a bit of work. You could just use apt-get to install them with no work on your part.