Yes, this is Quantum Immortality in a nutshell. If the MWI is correct, it is impossible to die from a subjective point of view.
Yes but there can be no communication from one possible world to another (thus no cross-world awareness), because, think
about it, if I could communicate with another world, then the other world would by definition be in my world (where I define
my world as all parts of the universe that I can influence with a lightspeed communication), so it would just
be some other part of my world. Oops. The bottom line is that if there are other possible worlds existing, they can be of
nothing other than theoretical interest to us. Damn. So try to avoid running into any creatures weilding large scythes
or other sharp implements tonight.