RE: shot placement on hogs
Use their elbow as a reference. Their heart is low in the chest, just about right behind the elbow.
If your arrow enters at or above the middle of the top third of the body's profile....the hog's gonna jet on you and he'll run to the next county before he drops, if at all.
If you spine a hog, a quick follow up shot in the vitals will shorten any tracking job you may have to do. Sometimes spined hogs will get up and run, sometimes they don't.