That is a very broad question. You do not need Tableau, Power BI etc. You can create graphs from data within Mendix itself. See the documentation here: https://docs.mendix.com/refguide/chart-widgets/
But if you have already some data warehouse you could use OData to fill your datawarehouse with your data.
When you update your data is up to you and depends largely on the amount of data that needs to be refreshed and how important it is to see live data. All is possible. When you create your charts inside Mendix you can control this and when using a datawarehouse you can decide there when to use the OData connector to retrieve the data. And distributing can be done with the datawarehouse tooling and there are some marketplace widgets to show that data inside Mendix. But those are most of the time paid products and it is often easier to distribute from tableau or PowerBI itself.
And how the graph looks is something you decide with the help of your end users. Just talk to them.