Aliases are easy to create. Strings are much the most useful. A variable will not be carried over to subsequent shells unless you export it. Programs written using the shell language are called scripts. Defining these functions gives you a way of customising at a level of complexity higher than that of aliases.
Functions can take arguments just as shell scripts can.
X Windows X windows applications can pick up their defaults from a variety of places. Xdefaults sets up many defaults. Programs like hpterm have many defaults you can set. For more information on X Customisation see the Using X handout. Customising keyboards under X Please read about X and security before running programs remotely.