Your update and delete are probably not working for similar reasons, I'm not fully sure why though just based on the testing that I did.
Please give this a try, on your update page find the line that starts with this:
Just after this line in the code add this:
This will print out the sql for the update. If you get the sql for the update to print to your screen then we need to do some checking of this sql to see why it is not updating your db. If you do not see the sql then that indicates that the update is not being triggered properly.
Please perform this test and let us know the result.