Ok, so I can't give you much advice, because I'm an absolute noob myself, but I can say that I was on a 10% win rate a couple of months ago and am now on a slightly less embarrassing 40% win rate, mostly down to the advice from the good people in this sub.

I wanted to address question 6 because this is a problem that I've always had. Projectiles frustrate me for a number of reasons: I play Falcon and he gets walled out by a lot of projectiles, FG has lots of lag so it's hard to judge projectiles a lot of the time and it's all flat stages so spammers get an easy ride.

So, from noob to noob, let me tell you a story that I hope will help.

I was playing a Lucario on FG a couple of weeks ago. Their only strategy was to run to the side of the stage, spam Aura Sphere until I approached and then run away and start again on the other side. Spammers. Amirite?

...and they beat me. I lost. I've never been so salty.

Here's the thing: I don't know if this player was any good, but they didn't need to be, because I handed the win to them on a platter.

I was salty at the spam and frustrated that my level of skill and experience wasn't enough to get past the stupid projectiles, so I lost my head. I threw any gameplan I had out the window and started approaching carelessly, throwing out stupid, laggy moves and being hyper-aggressive in an attempt to get at my opponent.

Obviously, any spammer with even half a brain cell is going to lap that up, so they got lots of free punishes and damage. I lost the game for myself by not thinking clearly, getting frustrated and making rookie mistakes, which I imagine is exactly why spammers spam.

TL;DR: spammers are cancer, but getting frustrated and losing your cool plays right into their hands. Stay calm and cautious, even when being spanked, and you'll increase your chances of success