To what extent may and why are keys shared across block and stream ciphers?

What are the potential limitations of Electronic Code Book (ECB)? If one ciphertext block is corrupted during the transmission, all subsequent ciphertext blocks cannot be decrypted unless until corrupted block is successfully retransmitted. Repetitive information contained in the plaintext may show in the ciphertext, if aligned with blocks. If the same message (e.g., an SSN) is encrypted (with the same key) and sent twice, their ciphertexts are the same. It needs an initialization vector to operate.

Show all of the steps needed to encrypt and decrypt the ASCII message “YES” without a modular arithmetic calculator in an RSA cipher with public key (143, 7).

How may block and stream ciphers exchange keys, and why should they be different?