There is no reason to worry about Ohm's law, unless you are using a mechanical mod, electronic (variable wattage) mods will do the calculations for you. As long as you are using a quality battery and don't try to exceed the batteries continuous discharge rate you should be fine. On your mod the what you do want to stay concerned with is the quality of the batteries. Personally I don't like going over 50 watts per good 20A battery. So if you use 2 good 25R's, or similar battery I would stay under the 100 - 110 watt range. The calculation you use is 160 (max wattage) / 6.4 (the approximate low cutoff volatage of 2 18650's in a series) = 25 Amps + 10% for board inside the mod = 27.5A for each battery. If you were going to use it to it's full wattage you would need to have TRUE 30A batteries in it. This would narrow you down to the LG HB2, HB4, and HB6 or possibly a Sony VTC 4.
Since you are using it at less than 30 watts you will be fine with any good 15a - 20A battery. (30W/6.2V*1.1=5.16Amps)
As for what settings to run, only you can figure that out. There are no right settings. The only thing you can do is start low and work yourself up until either you are getting the vape you want, or it is starting to taste burnt.
If you have any more questions feel free to ask!
