E84 LCI - Looking to buy, found few issues - tips for new to platform?

[Tallest]

Thinking about picking up a 12 year old X1 with N20 engine for my parents.

Few questions, what to expect around 85-90k miles mark?

The car had already replaced shocks and struts, but still running original thermostat and fuel pump.

From issues I felt on test drive:

the steering wheel turned to lock either side does this funny kickback (very unhappy whirring noises) and when turning full lock while maneuvering on a parking lot - chirps like a belt noise type of thing. Is that common? Tensioning pulleys or smth?

The car also had a thumping noise in the rear when going over bumps but I never know if those are just tools or even battery in the trunk or somethign more serious. Any tips what to check?

Finally, I read these expeience diff issues on the front in particular as there is very little oil and if car has unever tyre wear etc the diff will act up and grind itself over time. This particular car had it replaced but - with a used item. So not really sure how to diagnose if the used on is good or not, any tips, would a knowledgeable mechanic be able to tell if the diff is on the way out?

The chain thing is done so that I dont have to budget for but the above things are worrysome.

otherwise I cant say anything bad about how it drives or how engine is in the city. I wont be using the car much, but looking for a decent price reliability combo adjusted for it being a bmw. Have had super positive experience running BMWs. So Im comfortable with BMWs, but on 4wd cars im a bit concerned how to ensure I dont buy a car with mesed up diffs and transfer casings, and is there much more to check on the X1 in particular (LCI model) with N20?

Many thanks, sorry for long post!