What is the stock jet size?
#53 is stock, but if your bike has a biturbo it should have a larger jet already, probably something like #57. If not it may be necessary to up-jet.
How do I derestrict the air intake?
Drill out the obstruction in the breather tube.
Will I want a bigger jet size when I derestrict?
In most cases yes.
I have a biturbo exhaust, what does that mean?
The biturbo is an entry level expansion chamber exhaust.
If I’m making all of these modifications will my transmission be fine with the higher speeds/more power?
Yes, it will be perfectly fine.
What are the sprocket sizes?
26 teeth in the front and 22 teeth in the rear.
Would I ever want to change sprocket sizes? and what’s the benefit?
Changing the gearing can gain you a few miles per hour at the cost of acceleration or the other way around.
Many things affect the jetting which makes it impossible to recommend the exact jet. Altitude, temperature, and humidity all affect the jetting. This means your going to have to figure out the correct jet for your bike/location on your own.