Various parameters are controlled by /etc/rc.conf. Most common tweaks include setting rc_parallel and rc_logger to YES and rc_depend_strict to NO.
Most people will do fine with NetworkManager. For static network configuration it's preferable to install netifrc and edit /etc/conf.d/net for their setup.
You can control who has access to and control of what by assigning them to groups. A more than full permission set for the primary user is granted by the following, consider reducing it to only necessary ones:
usermod -a -G video,audio,input,power,storage,optical,lp,scanner,dbus,adbusers,uucp,vboxusers USER
OpenRC can set the host name either from /etc/hostname or from /etc/conf.d/hostname, with the former taking precedence. Their syntax differs somewhat:/etc/hostname
reallycoolhostname
/etc/conf.d/hostname
hostname="reallycoolhostname"
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