My hat? Definitely not a mind-control alien, no.
1. can you instant karma the card fire drill that says "choose an attraction type and close all those attraction in ALL parks"
it chooses an attraction that you have. it affects you but it doesnt say directly to you.
so can you use the instant karma? if you do... you also name another attraction type? and close ALL those attraction type in ALL parks?
The test for whether you are affected by an event is whether something you control changed state. Any change in your park, your hand, your money, or anything else you control counts as "affected". You can reveal Instant Karma in response, and make completely different choices, providing that those choices attempt to affect the player who affected you. So in short, yes, if they close all Sideshows and get you, you can close all Thrill Rides trying to get them back.
2. The shakedown says when the city event is revealed... so competitors decide to pay or not to pay you AFTER or BEFORE the city event resolves?
As soon as it's revealed but before it resolves. The intention is to give players the knowledge of the City event before making their decision.
3. on the arsonist... what if the attraction closest to your main gate has no upgrades? it burns the next closest?
what if the closest has only one upgrade, it burns the other next closest one upgrade?
Arsonists only affects the attraction specified, so one defense is to not build a tall ride close to the gate - this is one way that you can use knowledge of the possible bad effects to your advantage. Of course, it means you can't build anything on the first attraction in your park, which will make for a slower start, and Blueprints harder to match...