To open the 'Pan & Zoom' pane in Visio, go to View and select Pan & Zoom.
The pane appears on the page. You can use this to navigate around the map you are working on.
Normal scroll goes up and down. Shift + scroll goes left to right.
Remember to publish your site after approvals, to update the Library.
When making changes to a set of maps, configure your Multi Map Root in Process Navigator to point at the maps you are working on. This way you can use Process Navigator functionality on all maps, rather than selecting specific maps in the Map Control Console.