General question

No. All you have to do is to start looking at what your opponent has done with his or her last move.

Just learn one or two openings for both the white and black pieces. Knowing end game strategies helps, but it's not necessary until you get to higher elos like 900 or above. Watching people play on youtube definitely helps with that as well. The more games you put in and review, the more your elo will go up.

The best advice I would have to keep you motivated is to learn traps that kill games in under 10 moves. Those are fun to do and they work in almost every elo. I think the 4-move checkmate got me up to 600 or so elo just on its own lol.

The best way to get better is to play more and watch strong players play. This will give you a good idea of the game and you will develop a keen eye for simple tactics and traps. Take note of the things you keep falling for and common errors you make, and learn how you could have done better.

Finally, you don't need to memorise openings. Just play more!

I'm currently in the 700's (10|0 rapid) and have never studied a proper opening. I use general opening principles:

Put a pawn in the center

Develop a knight to protect that pawn

Develop your remaining knight and bishops

Castle

Connect your rooks

Provide an escape square for your king

If at any time I can safely put a second pawn in the center, I will.

Every game is different, the order of moves is not set in stone, but those are the general hierarchy of moves that I consider, with the overall idea of controlling the center.

I have been at the 400 level, heck I was in the 300's for a while, and honestly blundering was the biggest setback for me.

It still is.

No, you do not have to memorize every opening, every endgame, etc. to get better. While some memorization may occasionally be in order, it is understanding that you should, and must strive for. That is, the true road to success in chess is to understand the fundamental principles and guidelines of the aforementioned facets of the game and how to employ them, in addition to basic strategic elements of the game. Clearly, the more you understand of these things the better you will become.

How quickly and how much you improve will depend entirely on how much effort you put into learning (i.e., understanding) these things. This implies serious study of the game. And the optimum way to go about that is via studying chess books and/or having a good, preferably titled, chess coach.

Know also that understanding does not happen overnight. Chess is not supposed to be easy. If it were there would be much less satisfaction to be gained in becoming better at it. As one of the earlier replies said, getting better is a process. There is no shortcut.

The following article is intended to provide examples of the sorts of things one should slrive to understand in order to improve...

Improving Your Chess - Resources for Beginners and Beyond.....

https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond

You might also like to check out...

Good Chess Books for Beginners and Beyond...

https://www.chess.com/blog/RussBell/good-chess-books-for-beginners-and-beyond

I'm losing rating if I quit before the start of any games, on the contrary I don't gain if the opponent quits, why so??

Make a new post, your question is not relevant to this topic.

You have aborted too often so you have lost the option for a while. All you can do is resign now. The option to abort an occasional game will come back to you eventually.

Your opponents evidently still had the option, because they had not used it too often.

#7 bro stop, that is literally cheating....