Franz Joseph
classical
The first half of the 20th century is referred to as Classical Modern
Beethoven
Yes
The 18th Century. The beginning of the end for the Classical era and the start of the move into Romanticism perhaps occurred in 1800 when Beethoven published his first symphony.
Classical music has been around for some hundred years. It first started to show up in the 1600's and early 1700's. But the period of classical music was between 1750-1850.
The modern orchestra was first introduced during the classical period. Classical composers developed the genres of symphony and classical concerto (solo instrument and orchestra). Among the pioneer classical composers stand F. J. Haydn and W. A. Mozart.
it was first baroque, then classical, then romantic.
Wolfgang Amadeus Mozart (Austria, 1756-1791) was born in the Classical Period (1750-1825), when composers wrote music by playing a melody on the right hand, and playing an accompaniment on the left hand.
Greece first came to prominence in the Bronze Age, but the classical period occured after the Age of Iron. It depends on how ancient you want to get.
The so-called sonata-allegro form was established during the classical period, primarily by Franz Josef Haydn and Wolfgang Amadeus Mozart. It became the traditional form for the first movement of a symphony and later for chamber music such as sonatas, quartets, trios, etc.
Today we don't have classical music composers. Classical music is period around XVI to XIX century, even part of XX century. It was pushed by, in one side, atonality (modern music) and popular music in the other. Now, it's possible that today's composers write in a classical way. For example, the Prokofiev's First Symphony 'Classical' or Stravinsky's Pulcinella suite. But, even, we can't talk of classical music nowdays.