Not really related to a bug or anything, but to answer your question: They are powered by a built in battery pack and they don't use a lot of power. Look up PAPI LED...

Those are landing lights for aircraft. Every real-life landing strips has those.

Try a Saline bag.

Sometimes it helps to be empty handed since you can stand closer then.
There can also be a difference between crouching and standing up.

I think it is a good thing that you sometimes have to go through a bit of trouble to pick up an item.

It is as dev0 said:
Only after you used alcohol, charcoal or antibiotics will you know that you were sick all along. Because you know now you see the message.
Get your wounds clean and after that get fed up again since only now you can get your health back. Do this for a bit and you should see a message saying: Healthy (on your inventory screen)

Server swap issue maybe? Did you log back into the same server?

I think it is a good part of a survival game that you sometimes have to go through a little trouble to get an item.

By the way here is a trick that can help: Unequip your weapon so you can stand a bit closer to the loot spot.

Shovel, Bat, Fists, Crowbar, Knife, Wrench and Screwdriver all do the same amount of damage. You CAN kill a zombie with it, but it just takes a hell of a lot of hits. They are only good for hitting zombies in the head and knocking them out with it.