FreeBSD always was targeted on running on servers. So if that's where you will run it then you should have minimal issues with drivers. If you plan to run it on desktop it might be more challenging.

Regarding sysadmin, I tend to disagree, I think it is the opposite, mainly due to great handbook they have (http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/).

As suggested reading "man hier" is a great way to understand the filesystem layout. I personally also really like clear separation between the system and applications. For example all ports/packages are installed in /usr/local including configuration files (in /usr/local/etc).