I think you have done a great job.
By stating the following, it is not my intention to be negative, just trying to be constructive, so please forgive.
A lot of these errors will be eliminated after changing the first two lines of your document from
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml">
to
<!DOCTYPE html><html">
The remaining errors are due to sloppy coding.