1) Do not spend the gold on crew training. Spend it on crew slots! Choose your favorite faction and get a 6th pilot slot there. Eventually you will level up the crew on par with the others.
Later in the game you will find the 5 slots to become an annoyance and way too restrictive. With all the different aircraft to choose from, 5 slots just don´t cut it.
Also you can stay longer in the (arcade-) game with an aircraft more.
2) The thing I skill first on any aircraft is the reload speed (until it costs 10 points), then I skill the pilot. the three most important skills for fighters imo are "keen vision", "awareness" and " reload time". To some extend G-tolerance comes in handy.