it may be a snug fit but it is doable
freestyle, dirt, street
Depends on the diameters of the bars. Usually, but not always, they're the same and can use the same grips.
It is cycling a bmx.. A bmx is a small bike with a low seat, the whole bike itself is small which is ideal for doing stunts, they have stunt pegs and grips and small gripped wheels, they have wide bars, type "BMX" in google images to see what they look like, people use them for hobbies of doing dirt track ramps and stunts ans ramps and skateparks.
I THIN A FIT OR A EASTER OR WE THE PEOPLE BIKE BUT 100% FIT
That's a bit like asking if a burger is better than a banana split. They're different bikes, menat for slightly different uses. The bike that fits the kind of use you prefer will be the better bike. dirt bikes are somewhat bigger, so they'll ride a little faster. A BMX will be more manouverable.
Use An Air Compressor!
That depends on what you are using it for. Obviously, if you are dirt biking, you should use a dirt bike, and otherwise use a street bike. Start out with what you are going to use the most - dirt (freestyle) or street racing.
I don't think a pro would use a £80 Bmx bike lol
A bike to use in a triathlon would be either a mountain bike or a ten speed street bike depending on the riding, do not use a bmx bike or you will be sorry.
BMX bike ramps are usually made out of material such as chrome or aluminum. They have to be durable enough for multiple people to use them at the same time.
it matters what you are going to use it for
Yes, if you can find the correct bottom bracket for the frame.