1) Look for National Wild Turkey Chapter near you. May be one, may not. If is, email an officer and they can give specific info for your area. Two, seek out the F&G bio for your area. That said, the WA and MO turkey seasons span the "rut" so I use a call to locate. Once in a while will notice a turkey though if is windy or thick underbrush then hard to spot without a gobble. The crow call can sometimes get a gobbler to call even if a hen call does not.
2) Calling is very important for gobblers that are not pressured. You can call one into your lap. If lots of hunting pressure then gobblers get smart and will respond to calls by silently, slowly walking up to you or they might ignore you. Hunting gobblers that have not been pressured is amazing. The box call is easiest to use and is just about the best option in "big country" that has wide expanses. The "slate" or pot call is good but takes a bit more skill. The "mouth" call is fantastic for close-in calling with soft calling sounds for the last 100 feet or so as wait for gobbler to get in shotgun range since can use without moving your hands so can hold the shotgun. Youtube has great videos to learn to use the box, slate and mouth style calls. So, to recap, usually you do not stalk a gobbler but instead locate with a call or just set up partially hidden by tree trunk, bush, a bit of camo netting to sit behind or pop-up blind. I wear a camo net head covering if not inside a blind. I try to get within 200 yards then set up. A turkey can see about 270 degrees and eyes move independently so if you move they will notice even if are partially facing away from you as you reach for the shotgun or work the box or slate call. Gobblers sometimes gobble and you then look to your right and there he is 10 yards away. I will sometimes wait 15 minutes after making my "last call" before move. Do not call every 30 seconds, etc. Call, wait, call, etc. I have made an almost inaudible hen sound on a windless morning and had one or more gobblers immediately gobble 50 or more yards away. My favorite situation is having two gobblers heading in "hot" from two directions pissing each other off while I make soft purrs and putts and clucks. A gobbler may take 30 minutes to move 100 yards while gobbling and might take 3 minutes. Do not call unless are set up ready to shoot. In MO we would "roost" gobblers by making a crow call at sunset then return to set up 100 yards from the roosting trees at sun break. I once was deer hunting whitetails in MO in a tree blind at eade of cornfield in November and just at first light a pair of gobblers flew down from a limb 30 feet above me. My walking up with headlamp on, climbing a creaky ladder and then sitting in same tree in the cold did not bother them until first light and I had no idea they were in the tree...I was looking for movement below so as they flapped their wings I though a helicopter was landing on my head. I have unexpectedly flushed quail, pheasant and grouse but nothing was a sound as those wing flaps out of nowhere.
3. I carry all three styles you mention. I got a turkey vest that has a cushion to sit on. The vest has pockets for calls, ammo, gps, candy bar, etc. A "big" box call is more awkward to carry but usually provides loudest sound that carries the furthest. The slate call has a higher pitch of call that can be "louder". The mouth call is for quieter, close-in work and can make call sounds much more robust and varied than a box call or slate. I prefer the mini-dome style of mouth call but just my preference. One of my brothers never got comfortable using a mouth call and the other likes the flat style mouth calls so they are not that expensive so get a few and see what works. May take a few minutes to get a sound from the mouth call but say "pluck, pluck, pluck" in bursts of air from deep in belly and should get a sound quickly. Then can shift your jaw and tongue to get more sounds. Do not worry what the sounds are just so you get sounds. You eventually will make a "turkey" sound and can then repeat. Can use a cupped hand near mouth to make it sound like more than one turkey spread out near you. You can combine the box call and mouth call to make it sound like lots of different hens waiting on the gobbler. There is a gobbler call that can be effective but I avoid on public lands as worry a hunter with cataracts might open up in my direction. There is also a wingbone call but I only use it for fall seasons which is more like "pattern and set up an ambush the next day" type of hunting. Spring hunting to me is more like archery hunting elk in the rut where you locate a bugle/gobble then close the distance and set up to call in the bull/gobbler the last 100 or 200 yards.
