🚀 go-pugleaf

Okay, so I downloaded the Neodoom megawad from the Doom Wiki, and I
have a few questions:

First of all, What the fuck??

Secondly: those rats.  They are rats, right?  They don't count towards
my kill total but they can inflict damage on me?  And what are all
these other weapons?  How do I even access them?  I just picked up a
new weapon, it made the new weapon noise, but no matter what number I
hit I can't seem to use it.  (I mean, it's nice to be able to lob a
grenade like we used to do back in the old Duke Nukem days but....)
And what's with all these bottles and magic bags and profane
whateverthehelltheyare?  Do I use them?  Do I just collect them?
There are mines?  How do I use them?  The dark black imps that shoot
blue stuff, are they supposed to be Revenants?  Is there a double
barreled shotgun?  Can I use the knife just like I used the chainsaw?
Why don't the radiation suits, you know, *protect you from
radiation*!? And what the hell are those things that look like super
Imps, but turn invisible every now and then and don't seem to want to
die and run like the fucking wind so I can't even aim at them?

I'm using ZDoom to play this; should I be using something else?  And
if so, what?