A more in depth guide to hunting, in terms of marksmanship. Since you probably are not at the point in which you can kill a bear with a sword quite yet.
1.
Hunt in boats, with a lot of rocks/arrows with a good quality bow/sling, with decent ranked Marksmanship.
Boars are the easiest of the three to kill. The strategy for boar hunting is slinging/shooting at the boar until it is at low enough health where it begins to run. At this point, it will become passive until it de-aggros. Don't let it de-aggro. Player movement speed at running is slightly faster than a boar, so jump off the boat when it begins to run and begin punching it until dead. As long as it does not de-aggro, you should be fine.
Deer are relatively easy to hunt with a sling/bow. The minimum marksmanship that you'll be requiring to even attempt in killing one of these is 50. Deer can heal themselves. So when you hunt them, you want to kill them quickly. Drag the deer away from the pack if there is one, they will heal the deer. This will make it harder to hunt them. Make sure you aggro them in any matter before you actually start dealing damage, as you'll want to shoot as soon as it twitches, (the little lunges the animal attempts when trying to attack you.) as this prevents it from running away. Just shoot after the twitches, and hope it dies quickly.
Bears are really easy to kill. They cannot heal, but will maul you if you are not careful. Inside the boat, just continue slinging at the bear from a distance after the twitches. It should not run. If it does, it will usually come back. De-aggro it as it approaches the shore, and take another shot. If you don't, a chance will occur that it will run before you can aim. Continue doing this, and you'll notice that it's eyes will light up. This fill the bear's attack bar, but this does not matter in ranged. All that does matter, is that it will not run during this state. Continue shooting until dead, and you've killed a bear.
1a. You do not need to have discovered the metal to wield the weapons, you only need to discover the metal to craft it.
2.
viewtopic.php?f=2&t=18450&hilit=prospecting+guide#p213759 This is a more in-depth guide to prospecting.
3. As explained, you need a dowsing rod to attempt to find a water source. The closer you are to the water source, the higher quality the water from the well will become. Remember that the direction you want to follow is the opposite to the point.