It's 1/8" width, but the length is determined by the size of the bike frame, and the size of the sprocket/chainwheel you're using.
It depends on the length of the chainstays on your frame.
they keep your chain tight
Guessing an 11T cog (sproket), maybe a custom 10T.
The standard BMX axle nut size for most BMX bikes is 3/8 inch.
inox or chain lube from a bike shop
No, you can just cut your chain with a chain breaker or just take it to a shop and they will do it for you.
The standard size of BMX axle nuts is typically 3/8 inch.
The standard thread size for BMX pedal installation is 9/16 inch.
You might have to either lengthen or shorten the chain, depending on if you're getting a bigger or smaller sprocket.
Bmx's don't come in sizes. They are all one size.
The recommended BMX bike tire size for optimal performance and control is typically around 20 inches in diameter. This size provides a good balance of speed, agility, and stability for BMX riding.
The recommended BMX tube size for optimal performance and safety is typically 20 inches in diameter.