Not sure to understand the 1) but if you want to see a chart that group 2 others charts you have to create a new report.
For 2) you can do it in the EazyBI Dashboard
If all your reports use the same dimension as Page in order to filter on them you can set it as Common Page, the filter will then be available on the top on impact all report using it.
You can find the documentation about how to do it here