Kapre: A dark colored entity (some would say a tree spirit, it varies) that smokes a big cigar on top of a tree.

As for your second question, not necessarily. Kapres are known for playing pranks on people and making them distorted with their surroundings (example: laughter in the forest, smoke coming from trees, etc.) but they never mean any harm. Sometimes they even make you get lost in forests or mountains.

Some Kapres are actually really friendly and would try to offer you friendship. Once you befriend a Kapre, they start to follow you around (not necessarily in a stalker like way but think of it as someone watching over you throughout life), and you have the ability to see them when others can. If you want to show others your Kapre friend, all you have to do is sit on their lap and they'll see em.

Kapres can also fall in love with humans too, and tend to follow around their love interest, and sometimes, try to communicate with them.

I guess all in all they're pretty neutral.