How to edit template content properties via sitecore rock?

Is it possible to edit content property via sitecore rock plugin for VS ? for example Item Buckets section

Sure, that is possible. As I understood you right, you have an item with its fields loaded right hand side in Sitecore Rocks, you you do see custom fields but do not see fields coming from Standard Template, including Bucketable.

In that case just do right mouse click somewhere on the right hand side part, where your fields are and select Standard Fields from context menu. This will show those fields.