Regarding the button positioning: you have a paragraph tag inside those four table cells:

<td>
 <script>... </script>
 <p>... </p>
</td>

Normally, a paragraph element has a top and bottom margin equal to the standard height of a line. Internet Explorer suppresses those margins when they are adjacent to the top and bottom boundaries of a table cell. Firefox does not.

In this case, it would be simplest to delete the p tag, as it really serves no obvious purpose.

If you choose to retain the p tag, you will need to suppress those margins yourself. You can do that manually by adding an inline style to the tag:

<p style="margin-top: 0; margin-bottom: 0;">...

Or you could add a CSS rule to do it globally. It's a little complicated by the fact that you have another tag (script tag) before the p tag in your table cell, so I'll refrain from posting a convoluted fix and recommend going with one of the two earlier suggestions.

Just a Thank You note to jscher2000 for pointing out a error that was made long ago, but was copied over and over again.