Thanks!

And no - you can use a dice to generate the first 128/192/256 bits of randomness, but the final 4 / 6 / 8 bits which are appended to the end are generated based on the hash of the dice-based randomness you generated. Note that those 4/6/8 bits (i.e. the checksum) take it to 132 / 198 / 264 bits in total - always a multiple of 11. That's because each 11 bits of data encodes a word. So the final word in any valid mnemonic will be determined in part by the hash of the previous words.

I've tried to visualise this in the 'Fingerprinting entropy' section. It's definitely a tricky one!