Re: certain ideas abour sf tech
Warp drive, as I remember, works by moving space through space, rather than the matter it just happens to contain. Energy requirements are phenomenal, and, even if a source of energy were found that could deliver (presumably vacuum energy or similar) the efficiency of using it required would need a lot of nines after the ninety-nine percent, or the ship and all its contents would be reduced to elementary particles, not merely plasmolised. Not the sort of technology you want near a planet.
Hyperdrive generally transfers you into a universe (technically a continuum, as 'universe' contains all the matter and energy that is) where either physical constants (in particular the speed of light) are different – and it is extremely unlikely that any form of life could adjust to changes in these laws, so the interior of the ship would have to remain in, or be sent back to, its original continuum, with only the shell coexisting in the two, or where the age of the particular cosmos is different, so if you find one ten minutes old there is one to one correspondence between a volume that would fit inside the Earth's orbit, and the entire present day universe. A few minutes on ordinary drive and, when you transfer back, you're a thousand light years from where you started (we hope in the correct direction). Screening for radiation densities available in a cosmos so close to its origin could be an interesting problem, though.
If you really want to get properly arranged gravity with no continuous power, you could plate the pavements with neutronium (the matter making up neutron stars) for the low gravity planets, underfoot, for the heavy ones in canopies overhead. The means of manufacturing (mining?) and machining neutronium are left to the student.