It might seem sacrilege to put an oil burner in an Alfa, but the 2.4 is a really good engine and you'll see from other owners that it seems to be good for high mileages (mine has only done 35k). It's main drawback is its weight which makes itself felt when pushing hard on a good twisty road, but this is easily sorted out.
Unless there's a good reason for having a Q-tronic then go for a manual. A diesel AND and auto would be going a bit too far! Good luck with it, if you buy a good Alfa then you'll never want another make again.
Using yesterday's technology, to create tomorrow's problems, today.