If you have ...
- The seed (set of words)
- The master private key (a long string starting with "xrpv")
Then you can get all the addresses that can ever exist with any path that you like as long as it comes after this extended key.

If you have ...
- Master public key (a long string starting with "xpub")
Then you can only get addresses that are not hardened

If you have ...
- Individual private key(s)
- Individual public key(s)
- Individual address(es)
Then you can't associate them together or find their master key.

If you have ...
- A master public key + a derived non-hardened private key
Then there may be a way for an attacker to find the master key.