Actually, I have already solved this problem on my own, so I don't plan on opening a support case anymore. I found a solution that fixed both the browser printing differences between Firefox and IE, and the fact that the images were getting saved into Laserfiche in a small format. It was definitely related to the Javascript I had used to rearrange my form.

The main problem was that I was trying to approach the formatting by creating custom HTML elements on the form in which I would place DIV elements and style them to achieve the desired look. Then I would use javascript to move various Forms input elements into place by targeting those DIV tags in the custom HTML elements. (I got the idea from this answers post, although my code was slightly different).

I believe the printing issues were caused by the fact that I was moving fields around using Javascript, which was creating lots of strange list structures that were affecting printing in IE. When I inspected the HTML, I could see that by targeting input elements by the auto-assigned IDs, I was in fact moving HTML <li> list items around in strange ways.

I don't totally understand why the form was importing into Laserfiche in a small format, but it was probably related to the size/style properties of the custom HTML fields into which I was moving the actual fields. I imagine Forms couldn't properly determine the width given the fact that most of the content was placed inside this nested DIV container structure inside custom HTML fields.

SOLUTION: I have since gotten much better with CSS, and I have been able to directly achieve the styling I want on the Forms fields without having to move them into HTML fields.