I recently hypered to a system, when I arrived, there was a Starspeeder 3000 (NPC transport) at the same spot, I was not above a planet, but I was able to enter the ship.
Shouldn't this ship have been moving, and therefore not possible to board?
Also, I left some keycards on it, so when the ship gets destroyed at the end of it's journey (as the rules state) will my keycards be destroyed too?
Its possible that the starspeeders are set open to all to allow their passengers to get onboard initially. The don't necessarily stay above planets, but they should move I think. Not sure quite how they are programmed to move.
As for your keycards, most likely they will be destroyed. Can you give an ID number of one of them so I could take a look?
From what I've seen so far, Starspeeders don't continue travel automatically after arriving at their temporary destination (i.e. after ascending/descending, sublight travel or hyperspace travel). During that waiting time, you should therefore be able to enter the ship if you are nearby. Maybe that's something that should be changed?
"On your left is where Darth Vader died aboard the 2nd Death Star. Coming up on your right, is the location of your grave (still under construction, please wave to your gravediggers)."