Changing my shell to Bash

One way it to use NetInfo Manager, which resides in /Applications/Utilities.

Upon Opening NetInfo Manager, select 'users' from the center column, then select your username from the column just to the right. Now click the lock and authenticate in order to make changes. Scroll down, in the panel below, to where it says:
shell /bin/tcsh
and select the tcsh with your mouse and change to bash so that it now says
shell /bin/bash
Click the lock again and quit NetInfo Manager. You'll at least have to quit Terminal and X11 and restart them to get the changes. You might have to log out and back in again, but I don't recall for sure.

You can change your default shell via NetInfo Manager (slightly scary since you can screw up your account if you change something else) or via Terminal preferences (easy but only applies to Terminal).

You can try using the chsh command. (chsh -s bash user)