These guys have pretty much given you top flight advise, Any atomizer will heat up, that is it's job, to turn juice into steam...
This is noticeable in the ProTank as well as EVOD and several other bottom coil clearomizers because the coil unit is in direct contact with the metal base and will tend to act as a heat sink and will absorb any extra heat that does not go directly to steam production.
As long as it does not get HOT, just consider it a bonus that you can warm your fingers with your e-ciggy.
NOTE: In the protank, when it gets low on juice, this heat will cause the air in the tank to heat up and expand. This can cause a few extra drops of juice to get forced into the chamber when you are not vaping (flooding) and will make it burble when you next go to take a puff. The same may happen if and when you go from a cold environment to a warm one. My solution is to either lay it downon a counter or tip it down for a few until the temperature and thus pressure equalize.
Your genuine Kanger coil heads are laser-micro engraved with the resistance, this can be found on the electrical contact stud on the bottom of the coil using bright light and good glasses.........
With fixed voltage batteries, 2.5 Ω coils may not produce enough vapor, try the 1.8 Ω instead.
At 3.7v (ego style battery) a 2.5Ω coil will give you about 5.5 watts of heat, a 1.8Ω coil will give 7.6 watts and yes just like your Edison incandescent bulbs, the higher wattage does give you more light (er... Steam)
The spinners, will give you the ability to control the heat to some extent by varying the voltage, much like a dimmer switch on your lighting system.
However MY finding is that spinners run about $20 to $30 dollars at the stores around me and I can mail order variable voltage mods for the price of two or three spinners ($50) I admit you still have to buy batteries and a charger, but I get the batteries for $5 apiece that are the equivalent of 1 $15 EGO or 1 $25 spinner and I can put 2 wee B sized batteries in my pocket where the egos would jab me in a sensitive place. My $15.00 nitecore charger will charge 2 batteries at the same time and is much safer than the basic charger you use for the egos.
Just some food for thought, but overall what you already have should work great for you, just keep in mind that the PT mini will only fit on an EGO threaded battery and if yo get something that is threaded in 510 you will have to get an adapter