There is not a timer on the dirt bike itself, you have to take it to a retailer and have them plug a machine into the computer of the dirt bike, it will display how many hours (off brands such as baja generally dont have the computer capability to read out how many hours are on the bike) for a street bike, you have to apply generally the same process
a 125cc motorbike
125cc 85cc
Yes, an A-class.
you take the box were the accelerator is and there is a spring and you move the pin in it
That depends on what country you're trying to ride in.
a 125cc varies between 65-85mph with a four stroke engine, and 65-up to 100mph with a two stroke
Same as the rest of the UK - 16 but only up to 125cc.
Not legally, you have to be 17 to ride a 125cc or less scooter on the road
The fastest 125cc motorbike currently available on the market is the Aprilia RS 125, with a top speed of around 110 mph (177 km/h). It is known for its sporty performance and agile handling.
16 for a 50cc, 17 for a 125cc - 250cc, 21 for any cc
Too many variables, call and ask your agent!
There are quite a few factors that will determine how much insurance costs, I would call a local agent for a quote.