You will have to do this one by one. This is a very painful process, so be careful when posting recurring events. When the administrator approves the event it will become definite , and it will show as in the public calendar. As the calendar administrator, you will get a message whenever someone posts an event so that you can inspect it, and then approve it or delete it by following the URL included in the mail. You can also approve events one by one, by loging as the calendar administrator, and by selecting the corresponding event.
Next time wait until the page has been loaded.
You will find a form that will allow you to modify what is shown in your calendar, like the background image or the name and URL of your organization. Remember that the list of administrators is a list separated by spaces. Do not put commas or carriage returns in between. First you will have to log as the administrator of the calendar. On the other hand the neighbors of the neighbors are not added to the list of related calendars.