First of all, Thou Shalt Not use several frames of reference at once unless you know what you're doing or you risk being badly confused. (Take a look at the Special Relativity section of the Usenet Physics FAQ, especially the discussion of the Twin Paradox.) Possibly, get familiar with spacetime diagrams (also explained in that FAQ).

According to special relativity, the duration of the set of instants B in your life such as there exists an inertial frame of reference such that B is simultaneous with a fixed event A happening in Andromeda is 2L/c, where L is the distance from you to Andromeda. (Now you do need experiments to tell whether special relativity applies to the real world, but any deviation from it --except due to gravitation-- must be very small or only apply to certain circumstances, or we would have seen it by now.)

I meant it as "are now".

I'd say that the concept of “now” needs a frame of reference to be specified (or implicit from the context) to make sense.

Because if it is now in existence, then I imagine that there is now some way to affect it; which in this case would imply time travel (and therefore at least some form of FTL travel)

I think you are trying to apply to Minkowski spacetime an intuition that only applies to Galilean spacetime (and even then, it's not an intuition that everyone shares; IIRC, there have been people thinking that instant action at a distance is counterintuitive and a reason to suspect that Newtonian physics is not the whole story for centuries, even before Einstein came along).