I have many questions about Terminator Genisys

Terminator Genisys is not a film that makes a whole lot of sense. The time travel shenanigans spend most of the runtime spiralling out of control, and that provokes a lot of questions about just what the hell is happening. Here are a few of mine.

Who felt the need for most of the first act to be a shot-for-shot remake of The Terminator?

How many different, mutually contradictory timelines are we dealing with here? Four? Five?

How did Kyle Reese immediately know that Old Arnie was a Terminator if he's never encountered this model before?

How did Old Arnie get back to 1973? Who sent him? Why? When did they send him from? Considering that this is the event that completely fucks the timeline, why didn't they explain it?

How did the T-1000 end up in 1984? Was it the same one that tried to kill Sarah in 1973? If so, why hasn't it been hunting her all this time?

Why do people keep casting Jai Courtney in things?

Why is Kyle Reese built like a brick shithouse? Do they still have protein shakes in the post-apocalyptic future?

How did Old Arnie and Sarah build a time machine in a garage in 1984? Did Doc Brown help them?

Did Terminator 2 happen any more or not? Future John says Judgment Day was August 29th 1997, so I guess not?

I can understand wanting to retcon Terminators 3 and 4 away, but did Terminator 2 have to go as well? Terminator 2 was fucking awesome!

Since Sarah time travelled from 1984 to 2017, does that mean there's a very confused T-1000 wandering around 1991 L.A. wondering where his targets are?

If Sarah wasn't around in 1991 to blow up Cyberdyne, why was Judgment Day delayed until 2017?

How does John Connor even exist in this timeline if Sarah isn't even pregnant on the day that is supposed to be Judgment Day?

Since the only way to make even a little sense out of this film is to have seen all the previous ones, why is there a lengthy prologue explaining the backstory of the future war? We know this already!

Matt Smith (henceforth Doctor Skynet) had clearly infiltrated the resistance long before the final battle, or else John would never have taken him to the attack on the Time Displacement Chamber. That attack must have been months in the planning. So why not just kill John before he even launches the attack to destroy Skynet, instead of letting him and then sending a Terminator back?

If letting its central core get destroyed was part of the plan somehow, why didn't Doctor Skynet sabotage the time machine so Reese couldn't be sent back? Did it want Sarah to be protected?

Why do these movies keep anthropomorphising Skynet? Do they want it to be less intimidating?

If Doctor Skynet wants to ensure its own creation in the "original" timeline, why not send Evil John back to 1997, since that's when the world ended in this timeline?

Why the bloody hell was Evil John building a time machine in 2017? Did he have somewhen else he needed to be?

If yes, why didn't Doctor Skynet just send him there in the first place?

Was Steven Moffat a script consultant?

What was the point of J.K. Simmons' character? I love J.K. Simmons, and "Terminator conspiracy theorist" is actually a pretty neat idea, but did he actually do anything to affect the plot?

Why does an incomplete time machine explode when activated? Shouldn't it just not work?

How does the exploding time machine destroy Evil John but not Old Arnie?

Is Old Arnie a T-1000 now? How does that work, exactly?

Are we really meant to believe that Arnie is 6 foot 6? Come on, guys.

Why would you try to recreate the pathos of Terminator 2's ending and then reveal that Old Arnie managed to survive? WHY WOULD YOU DO THAT.

Why do they destroy Doctor Skynet at the end, only for the credits stinger to reveal he's still alive? Isn't that just admitting that nothing of any consequence actually happened in the entire film?

Couldn't anybody come up with a better stinger than "Oh whoops the bad guy's not dead after all"?

Why am I even trying to make sense of this movie?