I have an 08 Ti (not the same engine though
- check the power steering. any noises get the fluid checked. many of them were supplied with wrong weight fluid it seems
- check for uneven tyre wear. easy enough to fix with a full alignment but not everyone gets it done. I have 18" tyres on mine, they're expensive enough to warrant the investment in a geometry check every once in a while, I suppose 19" are even pricier.
- is it Q4? There was an issue with Q4 saddle shaped fuel tanks not filling properly and a warranty fix for it
- check for notchy gear change, can be ameliorated by linkage adjustment and a change in GB oil (although it didn't work for mine). Apparently no problem for the box itself, but would be better if smoother and alfa don't consider it a warranty item (the notchiness) so negotiate a fix before buying (if from a dealer)
- Some complaints about creaking windscreens. Not a problem in mine but perhaps run it with the AC on full to see if yours has an issue. Windscreen can be reseated, I believe
Volumetric alarm means there's sensors that can tell if someone's in the car. check the standard (vv1 / vv2) against what your insurance requires
dunno about lifting trim, not an issue in my car.
we don't have the lusso model over here (I think it's called something else) but the Ti is the top spec model. Ask for a catalogue to compare but I think the seats, suspension and wheels are uprated over the other specs and side skirts are added. Maybe other things too, not sure
as for engines, I've never driven the 2.0 diesel but in a run off between the 1.9 and the 2.4 I would go for the 2.4 every time.