Hi every one,
I have tried last year for some months PC-BSD then I went back to Linux Ubuntu as everything was heavy and complicated.
More recently i have considered trying Open BSD, then I have again browsed the other BSD systems.
It looks like GhostBSD is a good and nice option. I like MATE, by the way.
This being said, I would like to ask some questions ...
a) a PHP and MySQL server : would it be harder on GhostBSD than on Linux ?
b) the "utilities" : I have been studying the Linux commands and wonder now what documentation I could get about differences between GhostBSD and the commands that work on Linux.
c) Networks : how would it be to connect in network the three computers (two laptops and a PC) that I have at home ? Does it take any specific hardware ?
d) Installing GhostBSD : would I just have to download the file that is on your file and launch it ?

a) a PHP and MySQL server : would it be harder on GhostBSD than on Linux ?

Most if not all the Web/server application you can find on Ubuntu is supported on GhostBSD/FreeBSD. All documentation in the FreeBSD Handbook apply to GhostBSD and setting a server on GhostBSD will almost done the same way, the only difference is GhostBSD have a desktop preconfigure. I can't say if a GhostBSD PHP and MySQL sever is harder to set up than a Linux PHP and MySQL sever. I have never set up a Linux server but it is not hard to set up under GhostBSD if you know what to do and were your config file are.

b) the "utilities" : I have been studying the Linux commands and wonder now what documentation I could get about differences between GhostBSD and the commands that work on Linux.

The FreeBSD base system command line like sed and grep is a bit different, but man sed give a well detail documentation of sed like grep and the other. and all software you install that you can install will behave the same way than on Linux.

c) Networks : how would it be to connect in network the three computers (two laptops and a PC) that I have at home ? Does it take any specific hardware ?

You do not need specific router of switch, but the network card in laptop in your PC, might or not be supported, most of the time it is wifi, but lately FreeBSD is getting better with wifi card. Broadcom is not well suported.
If your wifi do not start look this at http://wiki.ghostbsd.org/index.php?title=FAQ#Network.

d) Installing GhostBSD : would I just have to download the file that is on your file and launch it ?

Not sure to understand this question but ghostbsd iso only what you need to install GhostBSD.

Thank you for your reply.
Development tools, for C/C++ programming, or Python, or PHP : what do you have ?
MySQL, PostgreSQL ... what options do you have in SQL ?

Development tools, for C/C++ programming, or Python, or PHP : what do you have ?

It will be faster to tell me what you use, because the FreeBSD repository is big, and GhostBSD use FreeBSD repository. You can look on the FreeBSD ports software database at https://www.freebsd.org/ports/ you can find the tool you need. Lately I use sublime for all my development it a is all in one editor that suite my needs and I can customise for my need. You can find lot of tool that you use under Ubuntu that is why that will be faster to look for what you already use.

MySQL, PostgreSQL ... what options do you have in SQL ?

Yes and many more, see https://www.freebsd.org/cgi/ports.cgi?q ... &stype=all

It's impressive.

I have already backed up my files. I am just now doubting about how challenging might be to install GhostBSD.
"FreeBSD ports software" : I don't know how to handle. In Linux there's a quite easy command line for that. What are these "ports" ?
Downloading and launching executable files is what I expect when it comes to install a new application.
What has your GUI to make easier such tasks ?

The ports is building software from source kind of like Gentoo. Package are build from those ports. pkgng is similar to apt-get and octopkg is fork of octopi, which is GUI to install pkg.

A great site to browse/search FreeBSD ports: http://www.freshports.org