the first error:
Warning: session_start() [function.session-start]: open(/home/content/70/4273270/tmp/sess_et0ado6ult5k8q6meosemdnaq0, O_RDWR) failed: No such file or directory (2) in /home/content/70/4273270/html/WA_eCart/WA_eCart_Definition_PHP.php on line 465
is the cause of the other 2.
The first error is a problem on the host end. it is a problem with the session.save_path in the php.ini file, it is pointing to a location that does not exist causing errors on trying to save session data. you will need to contact the host to have them correct the problem.