I'd recommend you, too, to first learn the basics of the game... Because no matter how good plane you fly, online, the Il-2 is not an easy game, even against complete greentags.
The difference between Il-2 and many other WW2 flight sims published before(as well as some TV "documentaries" and especially movies, is that this time the "bad guys" can fight back. The best prop fighter series of the game from 40-41 is the Bf 109. 42-43 its the Fw 190. 44-45 is arguable, but both Bf 109 and especially Fw 190 are still very high in the list. They are never easy opponents, anything but "target drones" you can just blast out of the sky one hand tied behind flying inverted in a P-51, to exaggerate a little.
The real-life advantages of the American machines is mostly their very long range, meaning they dont have to fly back to their base after just an hour of flying at mil power, unlike 109, 190, Spitfire and most Russian designs(especially La-5/7 had very short range). Gaming wise they are usually pretty fast, not always in top speed but cruising speed, except the P-40 which is a bit of a pig. P-47, any version, has hard time in any kind of dogfight at alts below 6000m (about 18,000ft), and while it can take a lot of hits, its not a good tactic to take them from any bad guy, and the first burst might still kill you, and the quad cannons of Fw 190 actually usually do exactly that. At high alts, if you keep your speed up, you can outmaneuver most Fw 190s(dont try the Dora, or Fw 190 D-9) and even sometimes 109s, that will lack elevator authority there and burn out their speed at just slightest maneuvers. P-51 is as fast or faster than German aircraft, usually much better choice than P-47, but even it cant outclimb 109s, out-roll 190s and depending on altitude it might still be slower, ie. D-9 is faster down low and 109 K-4 up high. Personally I think the best prop fighter of the game are Mustang 3 and P-51-D, but there are lots of situations where other types do considerably better, generally best doesnt mean best in everything, ie. they still lack the punch(armament) of many other designs.
Its all down to what your machine can do, against what you're up against, in the situation you have, at what altitude. And knowing what happens around you. Its called situational awareness, or SA, and is the very most important skill for a fighter pilot right after basic flying maneuvers and skills. Of course you can still fail even if you had every kind of advantage on your side, but SA allows you to avoid such situations that someone with better "flying skills" might survive.
You will most likely very soon find out why P-38 was moved to assault and close air support in Europe as soon as enough P-51s were around together with later P-47 models that could carry enough drop tanks.
But dont give up early, remember that some of the guys you will have to fight have played flight sims since 1990s, and at least 40%-ish have at least 2 years. If you can keep up the first 6 months, you will have learned a lot and the learning curve is not that steep anymore. But its so long that no one has yet made it to the top, so under right conditions, anyone(or anything) is beatable.
Finding a good group to play with, or even 1-2 people, helps too. See you in HyperLobby.