Were there always conductors in an orchestra?

Answer 1

No.

Conductors as we know them first appeared in the late classical period, but there had been other types of conductor before that.

The first attempt to keep an orchestra's timing together was trialled in ancient Greece, where the 'conductor' beat the time with a stick, holding the orchestra together. The renaissance saw a return of this idea, where an individual could strike the floor with a stick or their foot, or in some cases tap a book, to keep time. Jean-Baptiste Lully died as a result of this practice. He was conducting a performance celebrating a return from an illness he had, when he accidentally hit his foot with a conducting rod. The wound became infected and he died. In the Baroque period it became more common for a harpsichordist or (rarely) a violinist to keep the piece together. The harosichordist provived a continuo to keep time, while the violinist sometimes played and waved his bow to indicate time when he was not playing. By the waning years of the classical period, the bow had been replaced with a rod and the instrument became useless to the conductor, resulting in the conductor we know today.

Answer 2

Yes and no - during the Baroque period the keyboard player of the continuo was often the one to set the tempo/start the piece, but the role of a stand - up - in - front of the orchestra developed as the orchestra grew in size during the classical period.

Answer 3

Orchestration (synonymous with Instrumentation) is done by an Arranger or Orchestrator, but many composers choose to do their own orchestration. While it is not necessary to be a professional Orchestrator or Arranger to orchestrate, some (and not all, by far) conductors are also capable of, and willing to write orchestrations.

Orchestration is a noun: the verb form is Orchestrate. Tchaikovsky was a master of Orchestration, meaning that he understood the sound of each instrument and how to paint emotion on his listener's heart by using them well, alone and in combinations. He wrote a book titled Orchestration (many great composers have done so) which indicated the best ranges and types of figures each instrument and instrumental group in the orchestra sounded best, and giving advice on how to combine them for best effect. When a composer or conductor analyzes the work of another composer for performance, they will look at the texture, flow, and how it was orchestrated.

Orchestration can be easily confused with Arranging, but Orchestration is just one aspect of Arranging: to arrange a piece/song, you take the melody of the original and create for it a new piece/song, either by making a new arrangement (order of parts, instruments/voices used, new bits introduced, new intros/outtros, etc) or by sticking with the original melody and treatment and just changing one of those facets. An arranger can make an arrangement as simply as taking a song's melody and putting in a different range (transposition), use different accompanying instruments, adding one harmony/counterpart or many, or as complicated as writing an entire orchestration or changing the mode/harmonization, etc. There are many tools available to Arrangers, Orchestration is just one.

That said, professional Orchestrators usually work from a very simplified score indicating the melody and descriptions by the composer of anything from the specific treatment and harmonies/bass to vague "make it sound like the world exploding" sorts of comments. Their services are used both by composers and arrangers.

Conductors are professional orchestra leaders, but they also have all the training necessary to analyze and write music. Many of them have turned this ability to arranging or orchestrating (the most famous examples are probably Leopold Stokowsky, who orchestrated Bach's Toccata and Fugue in D minor, which was used in the original Fantasia movie, and John Williams, who has orchestrated many of the best movies in the last 4 decades. Stokowsky (now deceased) was conductor of the Philadelphia Philharmonic; Williams has been conductor of the Boston Symphony and other major orchestras. Other conductors (Georg Solti among them) focused on Conducting (and often accompanying soloists and vocalists) and never felt the need to arrange or orchestrate or even compose.