Jebus Cross

Regarding skill improvement:
1. Well, LeBron and I, for example, played 2v2 – he was my teammate. You learn a lot just by observing how your ally plays.

Yes! These kinds of games are great for improving your skills – it’s just a shame you can’t watch replays of your ally’s battles.
As for how to learn, I personally just try to enjoy the game. When you enjoy what you’re doing, you start to improve much faster. So, just enjoy the gameplay – the game itself, not just the result. When playing against a player who is better than you, set goals for yourself in that match – try to achieve them and don’t worry about losing. Afterwards, look at your opponent’s save file and think about where you could have played a little better – where you could have had fewer losses, where you could have taken an objective earlier, where you could have built a longer chain of structures. That’s when your skill level starts to increase. And don’t forget about theory. Taking objectives can sometimes be paradoxical – for example, attacking a Vale on day 121 with three Consorts without a spellbook and only with your native army; or taking a Necropolis with a maxed-out tower on day 111 with 80 Imps and 1 Gargoyle, losing very little. All of this, and much more, can be found in the threads that Navukh linked to. So, it’s all in your hands. And as for mentors… no matter how good they are, they can’t teach you everything. The motto here is: HELP YOURSELF!