I have an iPad Mini which is perfect size for me incoming P4. Can I use maps/waypoints and follow me functions with the iPad even though it is wifi only?

If you are talking about using it with a P3, then no. The WiFi only iPads are not fitted with a GPS receiver, which is essential for Follow Me. You can still do waypoints and POIs and you can cache the maps in advance, it is just Follow Me that is excluded.