Hey inauspicious,
I'm Eric, the author of 3COL-RDMBANRR, and I have a Support Forum for any questions/comments/concerns about all of my themes. Since you're already asking your questions here I'll go ahead answer them here as well.
There are 6 files you'll have to edit if you want to move the sidebar to end up with a [sidebar] [content] [sidebar] layout: 404.php, archive.php, index.php, page.php, search.php, and single.php. I know it sounds like a lot, but you're only going to move around 1 short line of code.
Start with 404.php. Open up that file and find this code:
<?php include ('sidebar1.php'); ?>
Take that code and move it ABOVE this code:
<div id="content">
Repeat this step for the other 5 files. When you're done you should have code looking like this:
<?php include ('sidebar1.php'); ?>
<div id="content">
My time is currently limited right now so I'll have to get back to you on that image problem you're having with the text widget.