Is there a way I can learn the basics of competitive battle without actually embarrassing myself in front of real people?
You probably want to take a look at Smogon's tutoring program,
Battling 101. They will do sign-ups tomorrow, so if you are interested and motivated, you might want to take a look. They do not have tutors for Doubles and XY, but it is still a good place to start.
Also on a percentage based scale how necessary is it to have all IVs at a value of 31? Like I caught a Klefki that's 31/31/31/16/29/31 with a beneficial nature in the friend safari and I cba breeding. Would that be okay?
We are not sure what you mean with 'percentage based scale', but it depends on how you use your monster. For general bulk, 3 points will not kill you but for a frail monster, you need to survive and KOs certain other threats.
What you sould always have 31 IVs on is speed, except for Trick Room attacker where 0 is necessary. Every move can make an impact, even on defensive monsters like taunting faster, encore, WoW.
But assuming you are lucky enough to catch such a Klefki, it is not difficult in XY to take care of the last imperfect stat if you know that the Destiny Knot now guarantees five IVs to be taken over, especially combined with the Friend Safari.
Oh and will Froslass be banned this gen? I want to use her but I dunno if it's worth the trouble of breeding/grinding Friend Safari for good IVs.
That won't happen. You just need to watch out: Smogon does not allow Snow Cloak or any evasion based move, item, ability. Snow Cloak is still legal in VGC, though.