Intranet Installation (PHP/MYSQL/APACHE/SQLYOG)

Hi, just want to ask a rather *dumb question. I have been coding with php for many projects now but I haven't deployed any of them online. Anyway, I was required here at work to do a system, and it will just be used for our department.

I would just like to ask.. is it needed that I install php/mysql/apache on every workstation? Or do I just need to install it on the server alone?

How bout licenses? Coz I have only used php/mysql/apache/sqlyog for freelancing stuffs. They're free right? I mean, I can deploy the system with the use of those technologies here?

How bout in SQLYOG? I have seen that there is an SQLYOG for developer and SQLYOG Enterprise?

Thanx for the reply!