League-of-legends – How do the targeting mechanics of Ahri’s Ultimate work

This is straight from the LOL wiki:

http://leagueoflegends.wikia.com/wiki/Shaco_the_Demon_Jester/Strategy

The bonus critical strike damage from Infinity Edge will apply on critical hits from Deceive, in addition to the bonus magic damage the ability gives.

So to answer your question: Yes Deceive benefits from Infinity Edge. It stands to reason that it will also benefit from Crit Dmg Runes. With that said, the following has been taken from League Craft forum posts: http://forum.leaguecraft.com/index.php?/topic/6388-shaco-deceive-crit-dmg-runes/

Not sure about the math or the mechanics behind it, but I just tested Deceive at level 1 on a Master Yi at level 1 in a practice game, once with a full page of Crit Damage runes and one with some other random page that wouldn't affect the damage. All other factors were kept the same both times. Results: Without Crit Damage runes: 64 from the front, 80 from the back With: 85 from the front, 100 from the back

Of course, that was in June 2010...

Stealth can only be broken by a stealthed champion performing an action that breaks stealth.

Though not viable by any means, before the sunfire cape's damage was a unique passive, it was fully possible to simply buy multiple capes and follow an enemy champion around while stealthed, relying on the damage to slowly kill them.

In this case, Time Bomb reacts the same as if you cast it on a ward - because the target is stealthed, the effect won't be visible, nor will it break stealth upon detonation. The enemy would just get a sudden burst of damage with no apparent cause.