It's not well explained in game at the moment, but no, Snuff Out isn't affected by those things. Generally, if an ability describes an alternate method of determining its accuracy, this overrides the normal rules (but I again admit this is definitely not well documented.)
As for the Smite target 85 Power 70% hit spell, you have to compare it to its close cousins:
Storm Strike: 30 SP, Electricity type, 85 Power, 12% Shock chance, always 70% hit rate
Humble: 20 SP, Light Cooldown: 3, 70 Power, can't miss, but only can target > 50% HP enemies
Agony: 20 SP, Dark Cooldown: 3, 85 Power, can't miss, but cannot target the same enemy more than once per 6 turns
Basically, Storm Strike trades a higher SP cost for not having a cooldown, and trades the "can't miss" attribute for not having target restrictions, with a small Shock chance built in for gravy. A case might also be made that Electricity is a better damage type than Light or Dark: All 3 come up as weaknesses fairly often, but Electricity is far rarer as a resistance and almost unheard of as an immunity.
Still... a fair bit of this is personal taste too. If you prefer reliable, trustworthy strategies, Storm Strike isn't going to sound awesome. It's definitely a bit tiled towards high risk, high reward, and doesn't offer much possible mitigation of the risk. This is a lesser flavor I try to show in many Electricity spells in general. Many of them have uncontrollable elements or inherent risks in their use... but they all have that cute little chance to Shock, and Electricity has one of the generally best resistance distributions at the moment.