Experience redeemables are tied to account - it means you can create new characters and those reedemables will be there until you use it - but if you already used in on a character, upon deleting it you will lose all experience and will start from a scratch.
Experience was transferred two times so far: on the wipe in May 2017 and on USA and EU server merge in December of 2017. Most likely you played on PVP Global (US server) and also had an inactive Spanish character on PVP EU (EU server), thus, after merging, experience from PVP Global character were transferred to PVP EU account where you had a Spanish character. If this is not the case, that most likely you gave your steam details to another person as the game could not switch your character nation on its own.
Regarding the Constitution ship - it is a timed redeemable that was added on 12 September and will be expired if you didn't activate it within 15 days period.