Question: If only the Resolution was able to do galactic travel, then how was Fortuna able to do the same?
Infestation - S1-E3
Question: If the universe is around 13 billion years old, can the distances between galaxies be counted as a different units? Galactic distance is huge; could the distances be in trillion light years apart? I believe the age of the universe is different than galactic distances?
Answer: Yes to all questions. The best theoretical estimate is that the universe is about 7 trillion light years across. That is about 250 times larger than the currently observable universe. So, yes, using trillions of light years as a unit of measure is appropriate. And, yes, the age of the universe is a measure of time, and the space between galaxies is a measure of distance.
Question: The eels eat the fuel in all the Jupiters, other than the one in the desert. Somehow, the eels get in all the fuel tanks. We know that the Robinson's ship got them when their ship sank and flooded, so how did they get into all the other ships' tanks, and why wouldn't more eels suck down the fuel later added from the desert ship?
Answer: The Fortuna didn't have an Alien Engine. The cover story was the Fortuna was to explore Alpha Centauri but it was exploring the rift. The rift is what the Alien Engine creates and explains how the Fortuna was able to travel to a distant planet (what you call "galactic travel").
Bishop73