You can create custom dashboards from any view/object. The dashboards are located in the Reporting application. Regarding the types of information you want in the user dashboard, you will probably want to use the "My Dashboard".

The way you add something to it is by going to each view you want to add, filtering it according to your criteria, then opening the advanced search and clicking in the section "Add to Dashboard" and select the right one. You can then organize these views according to various layouts in the dashboard.

In order to get this dashboard as the first screen at the time of login, you have to move the menu so that it becomes the first menu of the first application.

Note that the Inbox is a sort of dashboard too. It aggregated all messages from documents (or specific status of documents) you followed. As an example, you can follow a project to get warned each time a task is blocked or follow all deal lost in the CRM, all invoices to be validated, etc. The messaging system is a very simple system that allows every user to fine select what events interest him.

The menu has also a mechanims of "Need Action". When there is a number of the right of a menu, it's because the user has a few documents to check. (e.g. 4 leave requests to approve). You can click on the number to get only the documents requiring your attention.