This build focuses on dealing insane amount of damage early and mid game allowing yourself to get fed so you can also rock late game

Is essential without a good lane partner you will most likely not be able to finish your foes in one battle. Later in team fight focus the "big guys" (you know tanks, tanky dps) start with a q and shred them down with your e and your passive so the team can finish them off. Another important aspect of your Kayle game is enabling escapes ulti your teammate, heal that teemo saving them now will most likely help you later, oh and don't be afraid to die take one for the team champ

Flash exhaust works well because it allows you to either catch up or keep them down while you pound them in the ground. You could also try flash ignite, ghost ignite, ghost exhaust.

don't bother jungling your team needs the creeps more, although the occasional red buff wouldn't harm you

+Good damage
+Enemy resists go in the ground
+Nice support for the team
-don't know, I haven't found any yet