I am not a pro, and I have no relevant experience. Here is my understanding.
There are at least two ways that the pneumatic tank gets air. One is with a micronizer that pulls in air, and the classic is the way you describe -- have a drain back valve or just a small hole down the well to let the water drain into the well. The drain back valve should have minimal leakage when the pressure at that point is less than some amount. The hole will drain back water when there is pressure.
If the drain back valve is working right, the main thing is to remove the check valve that is above ground, usually close to the tank. The same for the hole, except that the hole will cause more water to drain back, and the pump will need to cycle even more to replace the drained back water. Removing the innards of the check valve is the same as removing the check valve for this purpose.
Thinking about that check valve again, maybe it would be best to leave it intact in case you have a hole rather than a properly working drain back valve. I don't know. Maybe leave it there unless you get a bang whenever the pump starts. In that case, I would still have it removed when the drain-back valve or hole is removed.
The sniffer valve admits air. It should not come into play with the check valve out of action. You could put a tire valve cap on it, particularly if there is a little water leakage. These have a drawdown of about 25% of the nominal tank size. Normally you would want the drawdown to be such that the pump runs for at least a minute each time. Thus, if your pump pumps 10 gpm, you would want a 40 gallon tank. 44 gallons is common size. Since you will have extra water flowing back while you have your drainback valve or hole in place, you would be better off to select a bigger tank. I think for this purpose, a CSV with a small tank would not be the thing.
You should have the down-well drain back valve or hole removed the next time that you get the pump pulled.
While there are still tanks with actual bladders, you don't want one. The better captive air tanks use a diaphragm. Well-X-Trol originally came out with the diaphragm tanks. These are sometimes colloquially called bladder tanks.
EDIT: after reading LLigetfa's post, I realize it is important to cap the snifter valve with a tire valve cap to block air coming in, if you leave the check valve in place. This should limit draining out of even a hole. Tire valve caps have seals, where the caps made to go on a snifter valve pass air by design. A pressure gauge would also block air from coming in.
If I put a pressure gauge there, and kept the check valve, I would put in a gauge that measures vacuum and pressure, such as the Winters PFQ791.
http://www.supplyhouse.com/sh/control/search/~SEARCH_STRING="30-0-100" gauge
Currently I am thinking that not knowing if there is a working drain-back valve down there, I would leave the check valve intact (until the pump gets pulled in the future), unless there is a bang when the pump turns on. But I don't feel sure.