4. If you were a Spanish fighter pilot in 15 years, would you want to be in the "may be good enough" Typhoon or the "it's still good for 20 years" F35?
Phrased like this, I come to the same conclusion as you. But if we look at it from an other perspective, we could also find some arguments that might favour the Typhoon over the F35:
Taking your same Spanish pilot, in 15 years he might be happy with his Eurofighter, knowing that only in a few years he will be at the command of his SCAF. The SCAF he will be flying perhaps better because the engineer that developed it, gained precious know how from improving the Eurofighter his government ordered 15 years ago.
Personally hopeing that we Americans and Europeans still share similar values and still cooperate in NATO in 15 years (well, I'm Swiss, hence not really part of the discussion), the Spanish pilot wouldn't just relly on Eurofighters. European armies would dispose of a fleet consisting of at least F35, Rafale, Eurofighter, F-18 and Gripen. And giving those fighters missions they are best suited for, might even prove a benefit.
I personally don't belive our politicians will manage the craziness of pushing us into WW3. But let's assume they did and our Spanish pilot and the world have to suffer the horendous carnage in 15 years:
The US is in a full blown war with China, the US needs all the fighters they can produce, having a few FALs in Europe able to build Rafales, Eurofighters, F35s and maybe Gripens, too might come in handy.
As I said, I'm no expert on fighter jets, but it seems to me, from a strategic point of view, ordering at least some Eurofighters would be a good move for Spain.
Best regards and stay safe,