It's a sort of... shell that does anything you do, but better.
It is. But in fact, Power Armor is an internal exoskeleton reinforced with the steel (or ceramic for APA) plates, controlled by the neural interface (for t-45d only). So it have absolutely nothing to do with the combat armor.
Chi si ritira dalla lottaE' un gran figlio di mignotta!
I think that Power Armors should also have a sort of requirement in terms of skills. Dont blame me for taking ideas from Bethesda, but after all PA Traning is present also in New Vegas, so it should be treated as canon. I think.
It shouldnt. In F1 You get the PA by proving Your loyality to the BoS.
IIRC, Solar or Lexx (I don't remember exactly) said that someday it would be available to the members of these organizations, but it would be really hard to get it, so it wouldn't be farmable via quest.