The Concertmaster ... usually the First Chair Violinist.
The leader of the orchestra is the principle first violin Actually, it depends on what you mean. The principle violin player is (normally) the concertmaster, but he does not conduct the orchestra normally.
A concertmaster or concertmistress is the leader of the first violin section of an orchestra. They usually come on stage last and tune the orchestra. They are also usually the most skilled player.
That depends on the piece, but usually there are 3 or 4 oboists at hand (in case one can't make it etc.) and one English Horn player. Most pieces have 2 Oboe parts. Some pieces by Mahler or Wagner could need 4 oboists and the English Horn player.
Usually it's the principal/first chair violin, also known as the concertmaster.
It all depends on the orchestra and what piece they are playing. You will see the use of many different traditional and non-traditional instruments in the modern orchestra. In the classical orchestra it would be uncommon to see a trombone.
Màtè Szücs, Solo Viola Player of the Radio Orchestra of Frankfurt and the German Chamber Orchestra of Bremen.
Manoe Konings
An orchestral player is someone who plays in an orchestra like a violinist or a cellist.
Al Viola
A small orchestra typically has woodwinds in pairs, medium or normal orchestra has them in threes, and a larger orchestras has woodwinds in fours. This means: 2 bassoons or; 2 bassoons and 1 doubler (bassoon and contrabassoon) or; 3 bassoons and 1 doubler. This often varies, and composers sometimes purposely organize the orchestra unbalanced. 2-3 bassoons is often what you'll find, a professional orchestra usually has a standard of 3 with the option of having 5 (2 more).
That is a very difficult question to answer as asked. It depends on what orchestra, where they are located (for instance, a player in NY city would likely be paid more than a player is Memphis, TN), what part the player plays, and how often the player is used.
A band? A choir? An orchestra?