guitars

Hey guys, I'm sorry if this post comes across as super dumb but I was just wanting to ask for some advice about learning electric guitar.

Over a decade ago I inherited a guitar from a friend who took his life, I tried learning it at first but ended up getting distracted by life and dropped it. Recently though I saw it sitting and collecting dust and decided that, even if it was a cheap electric guitar, I didn't want it to spend its life like that.

So yesterday I got some new strings, a new (and better) amplifier than the $20 one I bought secondhand over a decade ago, and a couple books about guitars, one of them being a book with nothing but like 300+ different chords, I also fixed the intonation on the bridge.

So here's my questions:

I'm looking to try and play punk rock music (All American Rejects, My Chemical Romance, Red Jumpsuit Apparatus, stuff with that kind of sound). What chords should I focus on learning that would be good for that kind of genre?

And I'm guessing the chords are can be played by strumming all of the strings together at once or you can play the notes individually, one after the other?

Sorry again if this post is really dumb, I really want to try and make sure I don't drop this guitar again, I'd like to properly honor my friend's memory and give this guitar the attention it deserves.