BMX wheels are laced pretty much the same way as any other traditional bicycle wheel is laced. It's not exactly difficult, but you do need to keep focused throughout the process. There's a fairly nice walk-through of the process at www.sheldonbrown.com: or you can do a net search for "bicycle wheel building instructions" and you're bound to find a few more.
it turns the wheel
Yes you can.... you can put any hub, spoke, and rim combinations together...maybe a few ecceptions but you can deffinetly do that... just bring the parts to your local shop and have them lace it.
There are two different hub designs for BMX, freewheels and freehubs. You need to know what you have if you want to replace the sprocket by the rear wheel.
change out the hub
they can range from 46teeth on a chain wheel all the way down yo a 22tooth chain wheel.
With considerable effort. I'll post a link.
The only thing on a BMX regularly called a spindle would be the crank axle. Although I suppose one could use spindle for the pedals and the wheel axles as well.
u pull up your front wheel and push your feet down on the pedels and lean forward
Five. One for each wheel, one for the cranks and one for each pedal.
20'' wheel size ,and roughly 25 pounds in weight ^_^
Two, but this is not the same as how many speeds the BMX bike in question has. A BMX bike has a sprocket in the front, and a cog in the back and each is a gear, but is considered a single speed bicycle because two gears and a chain are required for transmission of rotational force from the crankset to the rear wheel.
Guessing an 11T cog (sproket), maybe a custom 10T.