I use a gambrel to clean them in the air.
Basically it's a metal pipe with hooks on either side. On the hind legs find the tendon right behind the knee and cut a slice in the thin spot. The tendon is strong enough to hold the animal. I have that on a chain drop hoist to make it easy to pull up or down.
Wild pig is not like store-bought pig. It is very very lean and can dry out when cooked. These animals are on the move 100% of the time unlike farm pigs that are penned up in a mudpit and fed at a trough. Because the meat is extra muscular and lean, you need to bard the roasts when you cook them. You can make punctures in the meat and add lard or fat, but I just do a bacon wrap and kitchen twine it in place. No one complains about it.
As for baiting them, corn. It's that simple. I have done the fancy rubs and sprays and diesel and jello mix stuff. But really, corn works the best and its dead easy. I like to toss it on top of mesquite clumps and let the pigs root the stuff up for me. Double duty - no free lunch, they have to work for it.
Traps work ok, and I do have one. Don't trust a trap, ever. Also, keep in mind that if you trap a sow in heat you may have boars hanging close by.
Bring plenty of gun, a .22 is not the correct response. I used a 30-30 and then a 270 for years but now I use a 308 FAL. Does the job brutally effectively.
They are 60% nocturnal, especially if they feel hunting pressure. I made a pig-light with red LEDs that runs off battery power. If you go that route, set it up a few weeks or months ahead and let them get used to it. Light + corn + 1 month of feeding them and they will come running. http://forum.northernbrewer.com/viewtopic.php?f=29&t=81090
I ended up adding a 12volt photo switch, like "Precision LCS-612D" if you search amazon. I think mine was made by someone else but it's essentially the same thing.
You should study up on their basic anatomy, something like http://blog.hsoi.com/2010/09/03/feral-hog-anatomy/
Your two options are heart shot and neck shot. With a neck shot the idea is that the hydrostatic shock of the round entering will break their neck even if the bullet doesnt and they will drop in their tracks. A heart shot almost always has them running a few yards - up to 200.. because of adraniline. If you trap them or need to put a wounded one down, a 45 acp in the spot right between the ear and the corner of the closest eye is a good way to go.
Not sure what else to say but good luck. Take pictures, be safe.