I do not agree with the responses you gave.

1 how old is language
2 period between speaking -writing
3 what factor speed it up
4 what is easier make language or learn it.
5 single origins? Multiple ?
6 speed of spread
7 is ancient sounding language ancient
8 Is language prone to change? So why is sometime changing so little

1 at least ~65K when the technology of Homo Sapiens Sapiens (HSS)
experienced in Middle East a "revolution" that lately gave prominence
of HSS over Homo Sapiens Neanderthalensis (HSN).
2 First manifestations of writting in perdurable materials are about
3 Infrastructural advantadges & Cavalli-Sforza have suggested
reasonabily that demic expansion
5 It can not easily answered, we know about the "born" of various
languages in some conditions (pidgins, idioma de señas
nicaragüense, ...)
6 [?]
7 [?]