Happened for me few times. Only happens if I store it in backpack. I think there's a relation between backpack shuffling and shotgun disappearing.

suggestion - bunnies. Practice on non moving AI is worthless. Go to chernarus/electro and there's bunch of targets - zombies. And after you shoot other player will show up.

After I got status to healing it took some time to recover colors, but it worked. Don't think it's a bug, just takes time. Try reconnect, maybe that'll fix it.

I agree only on bleeding. I wonder how much you can bleed out by being hit by fists in real life. I think items should go to categories sharp/blunt and blunt ones should not make you bleed or have a really small chance of doing that. Even with baseball bat you can't make people bleed a lot, not talking about fists themselves. On the other hand - if you get shot, knifed, axed or something - you'd definately bleed 100%.

Hmm... Actually you can, if you reach "Healthy" stage with your char. If you only eat 1/4 of tuna can every time to you see a hunger sign - of course it will appear quickly. If you eat and drink till it says "you're full" you can go half day without getting hunger sign again.