Zombie Hunting!
Answer.
The general rule is you can reveal your powers to close family & friends if you're sure they can keep it a secret. If in the line of supernatural duty you inadvertently reveal your powers to someone that's okay as well. If they have a camera then you must regrettably destroy it but of course compensate them.
Leaving the confines of your reality is purposely not easy. The higher dimensional beings can't very well have the masses escaping their lives thereby deleting potential mathematical probabilities. Learning the art of Astral Projection is probably the best shot for the average person since everyone does it as they dream each night.
Psychics have said that me, and the Mystic Investigations team will have our own private intergalactic vessel in the 33rd century that traverses the Virgo Supercluster taking down the forces of Supernatural evil. Since we own a fleet of ships with various crews I give myself the title of Admiral Xavier Remington.
Yes
Time travel always result in travel to a parallel Universe. The Universe doesn't allow for paradoxes. However it could just so happen that you're meant to do something in the past of the Universe that technically you already did in the past without your knowledge at this point.
Yes
Lucid Dreaming is just a way to work up to Astral Projection for novices. It's not necessary.
Yes to all except overexposure of powers that could trigger the Supernatural Secrecy Pact, and Angelic intervention.