The scrollCommand attribute changed to xScrollCommand to be consistent with other widgets that scroll horizontally. The view operation changed to the xview operation for the same reason. Chapter 31 describes the entry widget starting on page 437.
The delete operation has changed the meaning of the second index so that the second index refers to the character just after the affected text. The selection operations have changed in a similar fashion. The sel.last index refers to the character just after the end of the selection, so deleting from sel.first to sel.last still works. The default bindings have been updated, of course, but if you have custom bindings you must fix them.