I'm sure he'll maintain his current scoring levels at United, though I expect the levels of petulance to increase tremendously.
He doesn't just have to replace Abrahimovich's stats, he'll have to prove himself as Abrahimovich's replacement first, before the team can comfortable build their play around him. At Everton, he was the sole focus, and if he didn't recieve the ball he tended to throw a strop right there on the pitch. Half the time he's running around with his arms outstretched calling for the ball. Will be interesting to see how that manifests itself with the Divas at United. I'm predicting 2 months before sources start leaking issues.
Has quality, but wouldn't be the sort Fergie would have gone for, though on paper suits Mourinho down to a tee.
I still think he'll have issues with Mourinho. He may fit the physical profile of a Drogba, but the mentality is vastly different (might also be a generational issue?), and Drogba brought more to the game as well, punishing CBs for the full 90 minutes wearing them out. I would be concerned if this was a young Drogba, but not overly concerned with Lukaku.