Friendly fire is on quick match its also how you level your profile.
I wasnt having any hitbox issues, so not sure why you are, but I was occasionally having lag issues.
So far I have thought the multiplayer was pretty solid while I have ran into a few bugs in singleplayer, nothing too big in multiplayer and I had very fluid combat, maybe you just suck.
Singleplayer however I did have one gamebreaking bug however it is early access so cant be too mad yet, as long as they keep releasing fixes/new content.