I am hosting a simple static website via Google Bucket right know: Does the Bill look familiar to you? I am surprised by the high usage numbers.
Does there exist a Hitcounter for GoogleBucket-Websites?

How can I secure my bucket website with SSL? I tried to follow the Loadbalancing Manual, but somehow it doesn`t work.
As stated in the documentation
As you correctly stated using the loadbalancer is a recommended method to serve your content trough HTTPS. If you need help with this I would recommend you to ask another question with the details of the steps followed and the error impeding you to continue.
Using a load balancer will let you use Stackdriver to monitor the access to your account. Using Stackdriver you can get custom metrics and get the number of users entering your website.
Also discussing your Google Cloud Platform billing invoice in Stackoverflow is not recommended as it is not related to programming. If you need help with your billing you should contact the Billing support team of Google Cloud Platform.