can someone explain ship speed to me?

Basically , the pilots stats, speed, damage health prot, etc. Have nothing to do with the ship stats, the only thing that boosts ship stats is pilot GP, and then it’s multiplied by the star count of the ship, giving a power boost. As you cross certain thresholds, stats increase on the ship. This is also why, you can outfit a pilot with five dot mods that are junk, ie started out grey, leveled to 15, and they give the same amount of GP as a fancy high stat five dot mod . The only factor a ship cares about is the GP of its pilot, that’s it.

Ship speed is based on overall power not the fleet commander's personal speed. Chimaera doesn't go faster just because Thrawn runs faster on his workout treadmill.

Here you go bro, I've found this to be extremely helpful

http://www.crouchingrancor.com/ship-speed-simulator/

Thrawn's crew power is what matters — no other stat matters. If you check your enemy Thrawn's crew power, it will be higher than your own Thrawn's crew power.

Whatever increases your Thrawn's character GP will also increase his crew power.