Does anyone know of any good tutorials that show how to create tabs with listviews as content? Possibly also showing how to update lists on tab focus?
By clicking on a tab you are supposed to start an Activity. You simply fire off an Intent. What the Activity you start does and how it looks like is totally up to you.
If you start an Activity through a tab click then the default Android Activity life cycle kicks in which means that you can implement your list updating logic somewhere in onCreate() if appropriate for you.
I highly recommend reading up the articles and tutorials on http://d.android.com as your main problem seems to be that you don't understand how Android is supposed to work.