I think the first error is because of the & before url because it needs a character code & instead of & and it should still work.
It happens with several characters including = Look at the character codes here
http://www.tedmontgomery.com/tutorial/HTMLchrc.html
The last one means you have opened a p tag but not closed it so the div closing tag raises an error because of it. Your code
Code:
<p style="text-align: center;">
</div>
should have </p> after center;>
It means that you have opened a p tag and closed it immediately without any text inside,
Code:
<p style="text-align: center;"></p>
</div>
so you delete <p style="text-align: center;"> instead if you have nothing to put in it.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.