I just brought a 1.6 5 door 2003 black lusso, with 81K on the clock but engine rebuild by auto lusso 28K ago, no bose, cloth interior, FSH paid £1650 for it.
whoever is selling it should say what model it is but if not your have lusso bag bottom of car between door and front wheel.
Bose is normally written on the speaker front grill, BUT i have known for someone to just change the front grills. Also it is a little better than standard but if it hasnt got it dont let it put you off the car.
steering wheel controls for stereo, the cruise control, is under the light stalk
Warranty, i dont have much experience with them but just be careful what they cover most dont cover wear and tear and check out the parts and labour total claim amounts!!!
Buying an alfa is same as any other IMO just make sure its been looked after correctly, have the main services and been kept well and look at previous MOT's for advisories.
People are pretty good on here, if you find one say what you have foun and see what people think
"Necessity is the mother of invention."