This is amazing. Love the 1-roll HP / Class chargen. I do feel like save vs HP makes rolling a warrior even more of an advantage than it already seems to be. Also - by sticking to D&D conventions you're gonna have a lot of parties stopping to let their wizards nap (not unlike D&D itself). I say this as someone who's 1st D&D character was a 1-HP wizard who cast magic missile once and then promptly died.
But there's a ton of great stuff in here. I love that you packed a whole system AND a dungeon into this space!