To copy information from one visit to another, be in the visits table and duplicate the patient's last visits record then make your changes.
As for display the data from the last visit directly on the patient's layout, there are a few ways:
1) You can sort your Visits layout in descending order (from the graph) on creation date and place the visits fields directly on your layout.
2) If you don't want to sort your relationship, you can place one-row portal based upon visits. Sort the portal descending on creation date and put all your visits fields in it.