The Kessel Run was said to have black holes and it wasnt a race of time, but shortest distance from start to finish, the navicomputer (L3) had the best route to find a short way to the end. Lets say its a foot obstacle course with the winner using the least steps to make it to the end
Yup. You could plot a relatively safe course through it, along known routs, but it required a lot of stops, and realignments, and recalculations to make sure your nav computer still had all the right inputs. It also involved giving each black hole as wide a birth as possible. "making the run" implied you were trying to push the limits, go as close to obstacles as possible in order to shorten the distance and time it took you to get from kessel to your destination. Half of it was that the better and faster your ship could go, the closer you could skim the black holes and still escape being sucked in (star wars logic, I'm under the impression this would not apply in real life
), while the pilot's ability to plot, maintain, and adjust his course on the fly made up the other half. Meaning the 12 Parsec run was a true testament to both the raw power and reliability of the Falcon, and of Han and Chewie's instincts and ability.
all together, I'm pretty happy with how they portrayed it in the film. making it the "maelstrom" gave them the ability to
visually get across the same idea, in a very short amount of time. the point being that there was a safe, slow, rout, or a very dangerous, bordering on suicidal, faster rout (into the maelstrom). And they also had the Maw and the... "carbon-bergs(?)", both things that harken to the EU's version of the run. It let them not have to spend half an hour explaining black holes and the nature of how hyperspace works, but still tell the same story.
Why was the empire even using trains? They have transport ships.
They've established trains, hover trains, "tracked conveyance" and land trains in star wars a number of times throughout the years. Generally, they're there for plot reasons; "you can't have a train heist without a train". They've often explained it away as being a preferred method of transportation in severe environments, where non space faring shuttles and starships have issues with the atmosphere. Worlds that are prone to sand or ash storms that could cause a shuttle to crash, won't cause a mag lev train to stop. Or an extremely cold world where it's difficult to winterize aircraft, a train or a land train (one big ass crawler dragging 200 unpowered trailers behind it) could more easily be kept running. remember, they were using air speeders on Hoth because they were the only ships they could winterize well enough to do patrols with. Their x-wings kept crapping out in the cold. In addition, even if a sand storm or the cold overcame a train or land train, it simply meant that the cargo showed up
late, instead crashing into the ground and being consumed in a ball of fire.