I found the solution to my first problem. That was, how to change the width of the Categories and Archives widget (which is sidebar_left.php). To do so I opened the file called style.css, scrolled down to the section entitled "Left Sidebar" and change this:
Now I have my Categories and Archives widget aligned with my eNews and Updates and my Recent Posts widgets. (See new attached image)
What I still can't figure out how to do is to add more widgets which are the same width (320px) under my existing widgets like they've done here:
Sorry for replying to my own post but hopefully this will come in handy to someone else needing the same thing.