I think yes just not sure never tried it

Yes, I've copied and raided my favourite seed a couple of times for frost caves.

New crafting recipes are tied to your character and can come back to your old world, as well as new resources in your character's inventory.

Yes, you can. You can in fact create multiple worlds with the same seed to try all kind of different things. Just remember to give them a different name, as naming it "Super seed" each time won't work well. ;)

Thorin :)

Nice