I wouldn't want Rooney back on the Everton playing staff. He would simply slow up the playing style. Personally, I hop Barkley stays, if not there is money to replace him. I would hope somebody like Gylfi Sigurdsson would be a better replacement than Barkley.
To me the main reason that Everton tailed off so badly towards the end of the season (other than there was little to play for) was the loss of Coleman. Effectively, you can leave the space in front of him open when attacking. Without him we often had no width down the right and mounted little threat down the left. Hopefully he returns in one piece with too much compromise to his capabilities after his injury.