Benefits of Bech32 addresses?
Native P2WPKH Unspent outputs save 22 bytes as their ScriptSigs are empty instead of 0x0014{20-byte-key-hash}.
2)
Yes, there's already a checksum of the same length.
The newer checksum algorithm is

Faster.

Very high probability of detection guaranteed..

Can find where the errors are: http://bitcoin.sipa.be/bech32/demo/demo.html (Press &quot;address with errors&quot;)


Also, you might be interested in the list of Bech32 Advantages.