I would assume so, since Hoid brought the flute along with him, as well as the bead of lerasium. If you're using a spaceship (ala Sixth of the Dusk), of course you can bring whatever.
Regarding taking people with you: Hmmm... We'll see. There are people who say you have to have the right type of Investiture to travel between worlds without technology (presumably through Shardpools, but that's unconfirmed). Anyone else know for sure?