As stated above, just adjust the watts on your MVP2 until you get what you consider to be a nice vape and then leave it. If you change out the coil in the future for a different resistance, the MVP2 will adjust the voltage automatically to keep you at that same vape experience (for all intents and purposes). As to what wattage you'll end up liking, well, that's going to be a personal relationship between you and your gear and juice - no hard numbers for you, just adjust until you're happy.
If you really want to know the relationship between volts, ohms, and watts, just google Ohm's Law - you'll get all the info you ever wanted about the mathematical relationship. Some (mostly older) devices had you adjusting the volts to get the vape you wanted, and changing the ohms of the tank's coil meant you had to readjust the volts to get back to that original vape. Setting wattage takes care of the voltage adjustment for you.