I'll give you a simplified answer to get you started. You can look for more in depth on the forum.
Pilots are one stat (yes the people in denial still buy/sell multiple stat pilots for high credits). The only "secondary" stats you would look for them are repair/restore.
So if you wanted a fighter look for a +12 Fighter etc.
So an elite (+13) would be better than a +12 (except perhaps if it had high support stats but that's a preference).
For classing never make it a Squadron Leader. Whether to make it an Ace is up to how many vets you might want but never go beyond that. Calculations-charts-reasons can be found on the forum.
One more minor tid bit - skip the rookie pilot stage for fighters and bombers. It doesn't add anything except Air which are not used by those classes. What this does is build up a tiny extra bit of support stats. So at 12 class to special, and leave it until 40 where you class to rookie and fighter all in one go. Nothing lost.