1. Fear. Mainly the kind of fear you have when you wonder if you're going to ruin a game for yourself by cheating so hard you get jaded to the whole experience, except in this case the stakes are much higher, your whole real life is at risk of having the magic sucked out of it since everything is at your fingertips.
2.First, I would weave an enchantment into reality that would influence all sapient beings everywhere into becoming kinder and more compassionate and understanding beings, Then learn how to obfuscate my knowledge about my power, and partially seal it so that I have my ideal powers without being so stupidly overpowered that everything is boring. With, of course, the ability to recall my full power should a truly unacceptable circumstance develop.
3. I wouldn't tell anyone.
4. N/A but if someone found out somehow, I'd probably just erase their memory of the situation.
5. I would definitely learn how to travel between dimensions, in any case. I'd love to visit all of the worlds writers have made.