I think Julian's Doc Savage/Jor-El analogy is apt --Jor-El was perhaps the greatest scientific genius and adventurer in Krypton's history (and perhaps in the entire galaxy). The invention of the Phantom Zone and Jor's interstellar adventures are indications that he could create FTL or even warp drives.
(I would like to see a brain-off between Jor and Lex Luthor!)
On the question of Krypton's distance from Earth, as usual Supermanica is very helpful in terms of canonical truth:
The distance from Earth to Krypton has never been measured with absolute certainty, but scientist Mel Evans has estimated the "probable distance at 0.317 light years" (S No. 136/2, Apr 1960: "The Secret of Kryptonite!").
https://www.supermanthroughtheages.com/wiki/index.php/Krypton#Astronomical_and_Planetary_Details