It all worked fine, slightly easier that Trixbox perhaps, and no weird forum registration required, and its pretty clean with FreePABX being the main interface.
However, my CallerID lookup and the CDR reports were not working. A bit of googling and I found this page - http://www.freepbx.org/support/documentation/howtos/howto-add-asterisk-addons-for-asterisknow-1-7 - which gives a way around the CDR, but that still didn't fix the CallerID.
To resolve the CallerID not working, I needed to install asterisk16-curl. So, to get things working completely, you need to:
yum -y update asterisk16
yum -y install asterisk16-addons
yum -y install asterisk16-curl
And then reboot or