Vythonaut: Sounds like a good plan; that way you'll be able to learn the game mechanics well enough to tackle the increased difficulty later. And just for the record, just checked out the achievements and it turns that an achievement for beating the game on Hard it does exist. :)
bomiboogie: Thought so. :)
Actually, I started on Normal, but figured that I learn more if I pay close attention on Easy, and maybe after a few upgrades, I'll start normal.
Also, I still don't understand the permanent upgrades' mechanism, so that comes first. :)
There are none.
You unlock pilots by meeting them in-game and achievements are stars to buy new squads.
You may carry over a surviving pilot from a playthrough to the other and they will keep their stats. But you don't have to, you can choose whoever you've unlocked already (at 0XP).
And that's it, no permanent upgrade.