Xcode vs TextEdit “Find and Replace…”
Here is a Part solution for setting the focus for ⌘⌥F

Save this Applescript down as a Text file instead of a script.

#!/usr/bin/osascript
tell application "Xcode" to activate
delay 0.5
tell application "System Events"

    tell process "Xcode"

        keystroke "z" using {command down, option down}
        delay 0.3

        keystroke tab
    end tell
end tell


In terminal.app

Make the script file executable by running 

chmod  +x /path/to/foo.applescript



In Xcode  go to the Preferences-> Key Bindings Tab.  

And change the Find and Replace (menu) 's hotkey to ⌘⌥z





Now still in Preferences go to the Behaviours Tab

Click the '+' button to add a new custom Behaviour.

Name it and give it the hotkey ⌘⌥f

On the right hand pane of the Behaviours Tab scroll down to the bottom

And using the Run  dropdown choose script. Select your Script file.



Now you can use the ⌘⌥F and the find and replace will appear and focus will go to the replace field.



As to replicating the keeping the Replace in view if it is already showing when you hit  ⌘F.  I think that in most cases it is redundant because you will want to still hit ⌘⌥F to get back to the replace field and the Find's text field will still be show with the changes you just made.