You're in luck because there is quite a bit of information regarding suspension on this forum. Just look up 'rear suspension' in the search field and you should get quite a bit of reading material.
Regarding your rubbing issue, where and what exactly is rubbing?
Your shocks are more than likely due for a change. When replacing shocks it is generally a good idea to also change all accompanying hardware such as shock mounts.
Example: Items 1 to 7 along with
Item 5 on this diagram
If the spring is broken then items 8 to 10 should also be replaced.
Definitely replace both left and right at the same time.
OEM brand for the shocks is either Sachs or Bilstein.
OEM brand for shock mounts is Lemforder
This can be also looked up on fcpeuro.com or ecstuning.com or pelicanparts.com (obtain part number from realoem.com then paste number into search field on one of the sites). Be cautious of part numbers that are for standard suspension and m suspension.
Good luck, and don't forget to look up the info on this site as well as
realoem.com