In game you'll own a 300i, its value is a 300i. It just has a credit refund value of $0 because you didnt pay for it, and i guess they didnt want people getting codes and melting them for $60 credit a pop.
The ships will have wear and tear, and restoration to a point, but you'll never get it to pristine condition. Seems reasonable to assume that perhaps the mileage on a ship may have a relation to how new it can look, or maybe its tied to how many times its been repaired or the combined value of the repairs.
I think we'll see people restoring ships to working order but keeping some of the visual wear for stylistic purposes, while others will want it looking like new and paying the extra costs associated.
Havent heard anything about system repairs & replacements due to general wear & tear, only destruction from combat or collisions type stuff. So not sure about stripping ships down and buying replacements beyond buying upgrades or fitting it out for a different load-out. Dont see why they couldnt, but im not sure it makes for a better game. It could become a real burden if costs to operate it are really high, but im sure i read something about luxury yachts IRL, the general upkeep on those is said to be about 10% of the ships purchase price, per year! I suppose things like this happen on a more common scale with cars needing parts replaced, and its not because its been in an accident.