All gauges and sensors work in the same way - however they are not all compatible.
Each sensor is designed to 'sense' a value range and send a value to its gauge in OHMS. 
So they all do the same thing - in the same way - however each manufacturer makes their gauges and sensors with their own set of values. There is not industry standard.
When you purchase a gauge it will have information on the operating range and THE INPUT RANGE. 
When you purchase your sensor you need a matching set of operating and input range or the gauge will not function correctly.
The best way to be sure is to purchase both gauge and sensor from the same place.

Yes there is no reason why not! A Temp gauge is as important for a air cooled engine as it is a water cooled one. So how do we do it.
1.Air temp gauge. If you look at the digital gauges you will find a digital temp gauge with a probe sensor. You drill a 5mm hole in the tin ware surrounding your engine, insert the tip of the probe and bond it in with epoxy.
​2. Think outside the box.  Fit an oil temperature sensor and gauge. The only difference between a oil temp and a water temp gauge is ........NONE! So use the sump plug to mount your sensor do the wiring and, jobs done!

These fittings are great for adding a temperature or pressure gauge to an engine that does not have a tapping in it.
Fitting:
You order the correct size of fitting for the flexible rubber pipe on your engine. The size quoted on the fitting is the flange size not the flat behind the flange. So if you need a really 'snug' fit order 2 mm smaller than the internal dimension of your pipe.
Cut into the flexi hose. 
Pass the supplied screw clips over the flexi pipe.
Push the fitting into the open ends of the flexi pipe. A smear of washing up liquid will help it slip in.
Pinch up the screw clips. Be careful not to go too tight to begin with, you can always tighten up if you need to.
Screw in the temperature sender, you will want put some PTFE tape on the treads first. Sensors come in all fitting sizes. You will find that if you need to change the size there is plenty of meat on this fitting so you can drill and tap it to match your fitting.
The last job that you need to do is run a negative wire back to the battery.
​Then you should be good to go.

VDO Gauges do not come with wiring instructions, so......
The two large poles are used to hold the 'U' clamp that keeps the gauge in position and do not have any wiring attached to them.
The small pole that has a 'G' next to it is there so that you can attach the wire that is being run to the sender. Remember that the sender must also have a wire running back to negative on your battery. This could be the earth strap on your engine if it runs back to the battery.
The small pole that has a '+' next to it needs a (12 volt or 24 volt depending on gauge type) live feed from a switch and fuse. The gauge will draw 1.25 amp max.
The small pole that has a '-' next to it returns to your battery.
The red wire provides power to the gauge internal lamp. This requires 12V feed from a switch and fuse and will consume 0.05 amps when running. 
Please note there is no wiring for the internal lamp negative. there is internal wiring that takes that to the correct pole.
Please note. The Battery gauge - Volt gauge (12 or 24 volt) will only have two poles, so no 'G' pole.