4. I plan on using 55gr Remington ammo in .223. Decent choice?
Only for brain shots and shots right behind the ear, IMHO. I use heavier .223 as well, but only in those locations.
3. Anything in particular we should know about hunting hogs?
People will tell you that hogs are smart, have an amazing sense of smell, poor eyesight, and their organs are not in the normal locations. Hogs are smart, but "smart" often means that the hunter can't be acting really stupid or that the hunter might have to work a bit harder to get the animal than something else. Hogs aren't as smart as a 2 year old child, which does put them ahead of many animals, but that isn't saying a whole lot.
Pigs can smell well, but I have seen smart pigs stand underneath the treestand I am sitting in and not look up for me despite obviously smelling me and continually smelling the area, then, giving up and walking out into the open where I shot them. Just because they can smell things long distance does not mean they always know what to do with the information.
Some reports indicate that hog vision isn't significantly worse than humans, at least not when they have a clean line of sight. Being low to the ground, somewhat sunken eyes (some individuals), etc., they don't always have a very good field of field, but that isn't because they actually have poor vision.
As for the organs, their heart is located a touch more forward than that of a deer. For most hunters, the inch or so difference won't mean a thing.
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Primarily boars have a shield along their shoulder blades and running along on top of their ribs on their high back. This is a cartilage under the skin. It can be very sturdy and offers the hog protection. It is the stuff myths are made of. Some folks report Howitzer fire stopped by it and others claim success with a .22 magnum through the shield. Especially on bigger boars, a bigger or more powerful caliber is probably better than a puny caliber, or you can just shoot them in the brain or right behind the ear and not worry about the shield.
You can bait hogs, look for sign, stake out trails and wallows. You can stalk them. I hunt alone and prefer doing it from a stand. You can hunt them just about any way you want (within the bounds of the law). Some people run them down on foot and cut their throats with knives. I can't do that from the tree stand.