You can't expect a 1B model to perform as well as 7B or chatGPT, probably the best use case is speculative decoding or to use to fine tune for a specific use case.
No, speculative decoding has exactly the same accuracy as the target model. It is mathematically identical to greedy decoding.
You will see that tokens not predicted by greedy sampling of the target model are rejected. Ergo, they are mathematically identical.