In Pokémon LeafGreen, if you have not reached Celadon City then you cannot gain entrance into Saffron City because you need to head through the Rock Tunnel to Lavender Town then head to Celadon City...
1. you can but it is not quite the same in terms of taste as powdered saffron will be absorbed whereas saffron threads will not.
2. You should be able to, but : -
In a dry or semi-dry dish threads...