squeaking from the suspension = upper arm
knocking from suspension = lower arm
both are a replace when knackered item.
you have not mentioned checking the oil. the 2.0TS hates being ran low on oil so check it before test driving, ideally without the garage knowing your going to look at it... if its low on the dipstick walk away.
On oil, it is possibly worth mentioning that the TS will drink oil, or at least in most cases it will.
when test driving make sure the selespeed unit selects each gear quickly, smoothly and quietly. try the operation in both semi-auto and manual, using both paddles and the 'stick shift'. all should operate flawlessly.
also use all the revs the engine has, the TS loves to rev and is very rewarding when pushed above 3000rpm. if you change gear with the paddles at high rpm (5000+) and with your foot down the gear change should be noticably more sporty and quick than normal changes..
I hope these pointers help