Can one receiving address from my Wallet be linked to another from the same Wallet?
I'm not 100% sure, but as far as I know this is not (easily?) possible. The addresses used for sending/receiving payments are created using your initial private key (THe 20 word long seed) in a deterministic way. When creating a new wallet with this pivate key, the same addresses are generated. 

It is not possible to guess your private key having one or more of your addresses. I think it's also not possible to guess which private key has generated the addresses.

You should use an address only for one transaction.