- some powerplants will get changed in their stats - then you don't need to rebuy the ship.
- some ships will get different powerplants (bigger ones in all cases), then to get the new powerplant you do need to rebuy the ship (using 1 ship in between as Gabrielle said). But you don't have to, if you don't it will keep the old (smaller) powerplant. A list of ships affected will be made available upon release.
Also I do NOT think there will be any credit refund. - so save some money:)
2. you can work to get guard reputation green even now
Then in 4.85 you can head straight to guard system and buy the guard ID. You don't need guard IFF to be able to use the guard ID afaik.
Also your tag doesn't change when you are rebuying ships.
Igiss says: Martin, you give them a finger, they bite off your arm.