First off, when you get errors like the ones you describe, you should always check the "Valid XHTML" link that is in your Meta area of the sidebar. If you do that, you'll see that you have 28 errors. Many of them look like font tag errors. These errors will cause what is happening with your "pushed down" sidebar as well as the odd font formatting.
I'll bet that you are using the rich text editor in WordPress; and I'll also bet that you are copying formatted text and pasting it in to the rich text editor. The problem with doing this is that the formatted text that you are pasting retains its native formatting. For instance if you copy text in Microsoft Word and paste it into the rich text editor of WordPress, you'll retain the Word formatting - that's bad. Word is one of the WORST HTML editors out there as it puts in a lot of extraneous code and is also bad at closing tags.
If you are copying text from a formatted source, first paste it in to Notepad - that strips all of the fancy formatting added by the source program. Next copy the unformatted text from Notepad and paste it into the WordPress rich text editor. Then format the text in the WordPress rich text editor the way you want.
The alternative is to turn off the WordPress rich text editor. If you don't understand at least the rudiments of HTML then this is going to be a real shock.