For whom?
Beethoven 7 is always a good answer.
The Simpsons theme tune is a really good orchestra piece.
It varies. Ever hear the term "12 piece orchestra"? That's an orchestra with 12 players.
Phil Spitalny and His All Girl Orchestra
concerto
No, unless a particular piece of music calls for a guitar in which case the orchestra can be supplemented.
A concerto usually has three movements and involves a soloist an an orchestra.
A ten piece band, or in classical music a small chamber orchestra.
fur elise was a piano piece
The actual count and type of woodwinds instruments required in an orchestra is determined by the composer of the piece. Not every single woodwind instrument is used in every single classical piece.
Of course NOT. The guiro is mostly used in bands or Mexican band music.
Erhu is not suitable in the orchestra, because it only has 2 strings, and symphony compsitions for the violin are usually going beyond the 2 strings that the erhu has, which is middle D and A. The other reason may be, the materials used to make the erhu: the bow of the erhu is made of horsetail, and the soundbox of the instrument is made of snake skin. Therefore, it makes the 'voice' of the erhu sound melancholy, and occasionally it may sound like somebody crying. Thus, it is not suitable to be in an orchestra. But rather, a Chinese orchestra.
I would have to hear the specific piece to answer for certain, but it is most likely Lacrimosa.