Can't it be argued that if you don't review the unlikely positions of advanced endgame study you'll just forget them? Since they rarely come at lower levels, you'll get little practice in them anyway and so with all that required review it really starts to sap study time.
An aggressive repertoire

Apologies if this has already been suggested in this thread, but Silman's Endgame Course is really excellent. It is broken down according to what you need to know if you are at a certain level "C" player, "A" player, etc. Very clearly written and very practical.
What's great about this book is that you DON'T have to learn it all at once, but you can immediately use what you DO have to learn.

Yeah I learned those key positions, and I review them once in a while but I can remember them well and that's all I've needed so far. I just disagree that endgames are crucial for every part, there are some times like choosing to go into an endgame but no it won't teach you middlegame tactics and strategy deeply.

Aggressive players at the beginnign level like you and I will find success playing openings that allow open lines and files and that give us initiative. Great attackign masters like Tal, though, can make the most positional opening look like a minefield of tactics. The principles of attack are more important than the openings in my opinion. Get books on atttack and study them. Practice openings..play a lot of blitz to improve your tactics..you will improve..play all kinds of openings..playing the same one makes you predictable and easy to prepare for
"And it is exactly then ( which is probably 2000's) that I will study it more. I don't see why I couldn't learn it then any better than now when it matters more. Any more knowledge from me now would be pretty unnecessary as those positions wouldn't come up and could be better spent some other time.
Because it will then turn out that you have to change the way you think during the middle game. And that's harder than to do it right first time.
Or that's the theory, anyway. I didn't do it, but then, I've also been stuck around 1950 since years...