Here are a full list of files that you may want to edit, depending on your needs:

FileDo I need to change it?Description
/etc/fstab YES - required Mount points for all filesystems to be used at boot time. This file must reflect your disk partition setup. We'll guide you through modifying this file below.
/etc/localtime Maybe - recommended Your timezone, which will default to UTC if not set. This should be a symbolic link to something located under /usr/share/zoneinfo (e.g. /usr/share/zoneinfo/America/Montreal)
/etc/make.conf (symlink) - also known as:
Maybe - recommended Parameters used by gcc (compiler), portage, and make. It's a good idea to set MAKEOPTS. This is covered later in this document. Note that it is normal for this file to be empty in Funtoo Linux, as many settings have been migrated to our enhanced profile system.
/etc/conf.d/hostname Maybe - recommended Used to set system hostname. Set the hostname variable to the fully-qualified (with dots, ie. name if you have one. Otherwise, set to the local system hostname (without dots, ie. foo). Defaults to localhost if not set.
/etc/hosts No You no longer need to manually set the hostname in this file. This file is automatically generated by /etc/init.d/hostname.
/etc/conf.d/keymaps Optional Keyboard mapping configuration file (for console pseudo-terminals). Set if you have a non-US keyboard. See Funtoo Linux Localization.
/etc/conf.d/hwclock Optional How the time of the battery-backed hardware clock of the system is interpreted (UTC or local time). Linux uses the battery-backed hardware clock to initialize the system clock when the system is booted.
/etc/conf.d/modules Optional Kernel modules to load automatically at system startup. Typically not required. See Additional Kernel Resources for more info.
/etc/conf.d/consolefont Optional Allows you to specify the default console font. To apply this font, enable the consolefont service by running rc-update add consolefont.
profiles Optional Some useful portage settings that may help speed up intial configuration.