Were there many cars and buses in London WW1?

The answer will be in the national archives, at Kew. Vehicle registrations at that time were by county, but to arrive at an accurate figure for London you would need the statistics from the LCC, London's County Boroughs such as East and West Ham, and the surrounding counties such as Essex, Kent and Surrey, where buses, taxis and delivery vans working in London could have been registered.

That's just motor vehicles. I believe trams were registered separately. Horse drawn vehicles, apart from hire cabs, weren't registered at all, and they still outnumbered motor vehicles as late as 1918, and for a few years after.

Fascinating, isn't it?

Quite a lot of but of cars. But note that just before WW1 there were not a lot of cars anywhere on Earth.

London buses went to he front line, more than 1,000 London buses were requisitioned for war service - about one third of the London fleet - so still 2,000 buses in London.

Yes

Yes, just enough

Very few. The vast majority of transportation was horse drawn.

In 1914, there weren't many cars or buses anywhere. Not a scientific census by any means, but I did a Google Image search for "1914 London." The link is below. Count how many motorized vehicles you see.

https://www.google.com/search?q=1914+london&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjF7ZL-ncjOAhUBayYKHYUNBjYQ_AUICCgB&biw=1600&bih=800