So if you stood completely still in space, let's say ignoring any gravitational pull, your relativistic subjective time would pass faster than anything else's in the universe that's moving, which is pretty much everything since gravitational pull affects everything eventually even by the tiniest bit. However these differences are marginal until you hit speeds in the c-percentages so most objects wouldn't get to those speeds by accident, in comparison, the ISS travels at 8000m/s (or roughly 0.000027% of c) and has in its lifetime experienced roughly 1/10s in time dilation. So a human spending their entire life in a comparable orbit would get ~1s more subjective lifetime, compared to earth, accounting for all the bad stuff space does to your body, probably not worth it.

However the dilation is measurable and has to be accounted for e.g. by satellites because for electronics, these "rounding errors" can add up and cause problems.

The largest reference frame is the CMB. There is no absolute reference frame which is a fundamental part of general and special relativity.