Yes, though there are dialect differences.
For the same reason that English is spoken. The language evolved naturally.
Sign languages are as individually different as spoken languages, and, as an interesting side note, sign languages for dialects of the same spoken language may not be related. British Sign Language and American Sign Language are in no way mutually intelligible.
The Quechuan language that is spoken by the Quechua natives of NE Peru was the primary language of the Incan empire. The language is YAGUA
It is a language. In the same way that English is the language spoken by people in England and the USA, Kera is the language spoken by the people of Chad.
No. In Monaco they speak French, Italian or Monegasque. In England they speak English.
The Lak language is used mainly in Brittain, in the central part of Dagestan. Along with the language of Lak, the Dargin (or Dargwa) language is also spoken in this same area.
A foreign language is any language that is not your own. A European language is a language spoken in Europe.
The name "Sarah" is spoken the same in any language.
English can be either spoken or written. It is the same language in either case, it is merely being conveyed by a different medium.
Spanish is the language spoken in the country of Spain.
Kissing is not language dependent. It is done essentially the same way, regardless of the language spoken.
English is the main language spoken in Ireland. The official language of Ireland is Irish. It is spoken mainly in the western part or Ireland. There would be some variations in these parts, but they are largely the same.