BMX bikes all have the same size (20") wheels, so they're very similar in size. Doesn't matter that much as they are mainly ridden standing up anyhow.
Yes.
To accurately measure fork travel on a bicycle, you can use a ruler or tape measure to measure the distance between the top of the fork crown and the bottom of the fork seal when the fork is fully compressed. This measurement will give you the total travel distance of the fork.
Any 20inch forks will fit.
To measure a bike fork accurately, use a ruler or caliper to measure the distance between the center of the wheel axle and the top of the fork crown. This measurement is known as the fork's "axle-to-crown" length. Make sure to measure in millimeters for precision.
To measure BMX handlebars accurately, use a measuring tape to determine the width of the handlebars from end to end. Additionally, measure the rise of the handlebars from the center of the stem to the top of the bars. These measurements will help ensure a proper fit for your BMX bike.
The forks go through the head tube and headset, the stem anchors the fork and then the bars attach to the stem, so the answer is the fork and stem.
the fork gyro (if have) and stem and mostly important the headset
That's a BMX, and there's not a lot of difference between forks for those. AS long as you get the correct steerer tube length, any BMx fork would give you a rideable bike.
The Powerlite BMX bike features a lightweight frame, durable construction, and high-performance components. It is designed for BMX racing and freestyle riding, with specifications such as 20-inch wheels, a sturdy fork, and responsive brakes.
Depends on what's already on there, what's available, and how much clearance the bike has at the fork and frame.
You measure it. A ruler and a caliper are useful.
The main parts are: frame fork wheels (handle)bars saddle seat post cranks pedals