1. Variable voltage allows you to dial in your vape. You want to match up the voltage with the resistance of the atty you're using. Variable voltage allows you to change the voltage which will effect vapor production, flavor, and the heat of the vapor.
2. LR attys are mainly used for mech mods that only put out the 3.7 volts the battery produces. Its also used on Variable Voltage devices when people want a warmer vape.
3. SR attys are better for cooler vapes, and work best on Variable Voltage mods set anywhere above 3.7 volts.
4. I believe all ego batteries are regulated with the exception of eGO C(U) batteries which have the option of unregulated.
5. LR attys would work best on a standard ego. SR attys on a twist.
6. Dual
coils tend to have lower resistance, but produce more vaper and heat (because there are two
coils and two wicks to heat). Dual
coils will kill your battery a lot faster. I personally don't like dual coils.
Hope this helps... let me know if I didn't explain any of this well enough.