It would be extremely useful to add a Find button on the Find dialog, where the Find button searches the whole document from the beginning to end rather than from the current caret position to the end.
Next, on to the Replace dialog, the Replace All button should also start from the beginning of the document.
Search direction, forward or backward, may be useful to some users as well. I rarely use that feature but I have found it useful once or twice.
Lastly, although it could be ugly, returning the caret to the position (approximate would be great) in the document prior to invoking the Replace dialog.