If the internal nodes contain data, the tree is a B-tree. Splits can propagate upward to the root. Reverse splits On delete, could empty a page. Like splits, reverse splits can propagate to root. Need to map the nodes to pages.
Pointers are page numbers.
If you keep full keys at every point, you end up storing the same strings repeatedly. Store minimum difference keys instead. Duplicates Can be stored just like regular items. Can be stored as one big item. Can be stored on a separate page.