#2
It's quite pitchy. As in you're pretty out in a lot of passages. It also sounds like you're singing below your tessitura, chest voice usually should not sound that dull. Best way that you can improve is get a teacher so you can work on your technique, then build up from there.
#3
you need some work
I'm in the same situation as you..
you should find a teacher
one thing that I found helpfull but I should do it more is matching the pitch on your guitar.
for example E string play 1-3-5-6-8-6-5-3-1 and keep moving 1 fret untill your in 7 as start
move to A string do the same D and G
I usually start by humming and then sing lalalalalalalalala do it for around 15-20 minutes and then sing some covers and some originals
I'm by no means an expert but I found this helpfull