Is it correctly understood, that the transaction creator (A sends money to B) A, addresses the transaction to the hash of B's public key? In order for B to redeem this transaction later, he has to proof that his public key hashes to the same hash, as A addressed the value to.
And by this and the "sig", B redeems the right to the value, previously addressed to him/her.
Pretty much, yeah.
In order for B to redeem this transaction, they first have to reveal the public key of said address. The public key is verified by hashing it the same way that the address was originally created, meaning the hashed public key should equal the BTC address.
Secondly they have to sign the transaction with the corresponding private key. Now that the public key of said address is known and verified, miner / nodes can use this public key to verify whether the transaction was signed with the correct private key.
Btw the BTC address is slightly more than just a simple hash of the public key. For more details, refer to this wiki page:
https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses