Customized classic theme, lost some functionality

Installed WP the first time for a client and managed to customize it to their site (using Dave Shae’s classing template). I have three questions that some of you may find easy to answer, I can’t find it
in any of the help files I looked at:

1) Under “Appearance” > “Editor” gives a 500 server error, resource not found, why?
2) In the Sidebar, under Meta I can’t remove some of the menu items that I don’t want to show there. I just want Log in and rss.
3) Comments don’t seem to work. I can’t add one or see the form to edit it. I deleted the default comment (perhaps I shouldn’t have) and now the comment functionality seems to be gone.

Can anyone help me with this, or point me to the files I need to edit? Am going by the seat of my pants here, setting up/customizing WP the first time. Using a Windows server, don’t know php, but can understand the code somewhat. The URL in question is: http://northislandpartnership.ca/blog/ Thanks