Can I set my own custom error pages?

Of course. Goto My Domains > Domain_Name > Custom Error Pages and edit the pages to ones of your liking. Or you can point the page at a file or other URL of your choosing.

You can set custom error pages for 400, 401, 403, 404, 405, 406, 407, 412, 414, 415, 500, 501 and 502 errors.

For details of the options available for  Webhosting click here