There are many cars which offer hydraulic steering as standard in todays modern market instead of the alternative eletric power steering. One such example is the 2013 BMW 535i which comes equipped with hydraulic steering.
Only if it has power steering. Most all cars these days do.
Standard power steering fluid will do for most cars. Just look in the owners manual for the correct one. Or if you want call your local dealer and ask them
Yes they do have a version of power steering.
Power assisted steering.
yes.
Power steering fluid is basically clear. Some cars use transmission fluid in the power steering which is dark red. You can use power steering fluid in cars that use transmission fluid but not the reverse. The cap of the reservoir should say power steering fluid only.
Steering wheel size is pretty much standard and that is about it.
It is not illegal to drive without power steering. Many people who drive very old cars do not have power steering.
power steering
From what I understand, power steering in cars (vehicles) is simply to make steering the car easier. If it were not for power steering, you would have to use a lot more muscle to turn the steering wheel than you use when you have that power steering in place!
It is not possible to alter a car from a manual steering into a power steering car. The engines for the two types of cars are very different.