For older versions it is "/etc/lilo.conf" and for newer versions "/boot/grub/grub.cfg".
By "change port in Linux", I assume you mean changing the default port an application listens or transmits on. This is usually set in the program's settings or configuration file.
Most Linux applications store files somewhere int he user's home directory, either in a folder of their own (such as .applicationname) or as a single configuration file. Deleting the configuration file should return the game to the default settings. Alternatively, you can try modifying the settings file and fixing the bad resolution manually.
ext3 is the default file system for Red Hat Enterprise Linux.
/etc/lilo.conf
This file is a dns configuration file for Linux CentOS
text file
/etc/apache2
The Linux ext3 file system is the default system in many linux derivatives. It allows for journalling, which the ext2 system did not. It also allows in-situ upgrades without asking for a backup first.
NVRAM, TFTP,Console
ldlinux.sys is the name of the bootloader file used in SYSLINUX and ISOLINUX (used for booting Linux off of FAT32 and ISO9660 filesystems, respectively). It is loaded into memory by the BIOS on bootup. The loader then parses the configuration file (syslinux.cfg or isolinux.cfg) to know which kernel to launch, along with parameters to be passed to it.
/etc/passwd
You don't mention what you are looking for in terms of a "running configuration file". In Unix/Linux there are many of these. Most of them can be found in the /etc directory or its subdirectories but not all of them are located in /etc.