Isn't gravity defined lately as the curvature of space? There's no such thing as zero gravity in the manifest universe. Relative zero, perhaps, but not Absolute Zero. So the way to fake higher gravity is to keep a constant of acceleration. Relative to stationary objects, a spaceship might move the speed of light, but the lack of resistance of "blank" space would permit it to continue acceleration until it was overly influenced by the gravitational pull (friction) of a large celestial body. Within such a ship, the constant acceleration would be more meaningful than the speed of the vehicle. Reverse acceleration would have similar effect within the ship.

Frankly, I think the only way foreseeable now is nanotechnology and DNA encoding - like longrange cloning. Our nanobots swarm a planet with the right primordial soup and shoot our DNA into it. We either grow from the muck or evolve. Either way won't matter much, as the Earth will likely not be in touch with propelled space voyagers. I think the only longterm answer lies in technologies that facilitate space folding or dimensional teleportation. Which means we'll have to have a far greater understanding of subatomic particles, antimatter, dark energy, and such.

Maybe . . .

Wow! This gets really complicated very quickly.

Assuming no artificial gravity, as commonly stated, bone mass and muscle mass lessen. So the bones and muscles atrophy. What about organs? Metabolic changes would have to re-regulate or become aggressively adaptive. This would create changes in the pituitary down to the thyroid, adrenal system, hormonal systems, etc. Diet would come into play, and would have to evolve. If we're not using hydroponics or such to grow organic plants for food, we would likely need to adapt to a diet based on micro-organisms. Which would change our dental makeup as well as our entire digestive track. Eyes would definitely evolve to something else - I like to imagine that we'd develop a nictitated membrane to deal with changes in light, and that it would work not only to deal with light but to filter out other harmful radiations. Skin pigment would likely become unnecessary. Circulation would change because of the gravitational changes as well as the near-static environment as maintained by the computers onboard. Hair would either thicken or develop into colorless villi capable of organic processes to digest available radiation (radio-synthesis).

Would we retain our hands as they are? I think they would be very similar. We really depend a lot on that opposable thumb adaptation, so I doubt we're going to hold onto it for as long as we have carbon-based bodies.

Look into the deep ocean trenches and evolution around the vents. This might give you a lot of ideas on life in an environment cloaked from natural lighting. There are a lot of really creepy things down there! Also deep cave critters.

BUT, I really think that we'll have to have vessels with windows that let in certain spectra of light. Radiation and light will become necessary to feed Homo odyseus.

There's lots more . . . is this helpful?