Positioning

I’ve gotten my header to look the way I want it in my own Firefox browser but am having 2 issues:
1) I can’t put a table into the subscribe widget at the top, and it’s not displaying properly in all browsers, so I need to position the elements using CSS. How do I get rid of the space right before the email form. This shows up when I switch to border box model
2) My margins/padding are pushing my header wider than it needs to be (I’ve been told). First, how can I see this? And second, how do I fix it?
Would really appreciate any feedback, thanks!