If you have a dark wall then the marks left by the rubber feet won't be noticeable so that is a plus
Putting some tape over the screw/ hook so the pump is resting on the tape instead of the metal, will help to reduce the noise from the plastic case on the metal hook/ screw. And if the wall is hollow (with no insulation) it might make a bit more noise than a solid bit of wood. Having the sponge under the pump might help reduce that too.
Since the pump does have a dial to adjust the air flow, you do not need a T-piece and tap to bleed off excess air. Turning the dial down will reduce the airflow for you.
The link you provided does have 2 different pumps available. One pump is a single outlet, whereas the other pump is a twin outlet. The twin outlet pump should provide more air per side, and has 2 outlets to use. Depending on how tall the tank is, will determine which pump you should get. The taller the aquarium, the more back pressure that is put on the pump because it has to pump the air down deeper. If the tank is only 12 inches high then the single outlet should be fine. However, if the tank is 18 inches (or more) high, then the twin outlet might be the better choice because it will be able to pump more air into deeper water.
The pumps do have the same 2.61 psi rating so the internal diaphragm and airchamber might be the same size. In which case they will both be able to pump air down to the same depth of water. However, single outlet airpumps usually (but not always) have slightly smaller internal components (diaphragm, airchamber & vibrator arm) and usually produce less air in deeper water. If you contact the supplier they should be able to open the pumps up and see if the internal components listed above are the same size. If they are then that's good and you can use either pump.
Personally, I prefer the bigger 2 outlet airpumps because you can use the extra air later on to hatch brineshrimp eggs or in a hospital tank or to aerate tapwater and conditioner before adding new water to a tank.