One iteresting thing

When they send somebody back to the past to protec John COner
The one that protec are always older models and that means weaker.In the first movie the dude who Protects Sara COner isnt even a terminator.If i remember right he was just a normal human.

Thats a point, considering that the Terminators/Reese were sent back at roughly the same time in the future, were they not?

Well, when you think about it Skynet is the body that is equipped with all of the AI technology. The Resistance will always be a step behind because of the fact that the only closely available equal to a Terminator from Skynet is a captured Terminator itself.

Captured AND reprogrammed. Obviously no way to tell how long that would take in the underground slums we see in the original Terminator film.