13 years is not that old..., Also we dont know what price the bought it (it was not in used since 10/2009) and if it was really worth it (probably yes).

I would prefer EL-AL to have 4 more like those rather one new one, As it will
provide more flights / routes where needed.

As for the partial colors, since its not the first one, i would say there might be some kind of a way to distinguish between types of planes (like lease vs owned).