The clank when you go over bumps maybe the shock/strut mounts, the rears are a known issue.
For the body parts you could check with vinesauto.com your bama new/used BMW parts wonderland, they also have used parts search which is very handy.
www.realoem.com/bmw/ is very good resource, it provides diagrams and parts numbers for the entire car.
Also
www.e34.de/vin/ will give you a vin decode to tell you what engine and trans came in the car from the factory.
The oil change is easy just use bmw or oem filter because it is so small you need the best filtering, if you have a local filter you can use it the change just the filter later.
Good Luck! Keep us posted.
Dan