Hi there guarriman!
It's a matter of taste, really. However, I would not install anything at /home and most likely, everything at /usr/local/share. Some would say /usr/opt/. Well, whatever you do, put somewhere at /usr/
. By doing so, you just have to install the program once (as Firefox) and all other users will be able to use it. It also makes things much more organized that way too...
But then again, it's all up to you