I have heard that the way different languages describe colours (eg, if you have a separate word for orange and for red, or just call it all shades of red) influences how speakers of that language see colour.
Yes you're getting into a whole mess of language acquisition and development theory there
The Sapir-whorf theory of linguistic relativity. Shapes not only how colours are viewed but culture, society, politics, psychology... whole mess of stuff 
What I call in my own head the "dangerous minds" theory - "words are thoughts and we can't think without them" and the words we use to think and express ourselves matter.
Then Noam Chomsky (fabulous man) comes along and subverts it all!
Would my ancestors from 1800 have understood my accent? probably not - look at linguistic migratory patterns in the Uk at that time.
I have an odd ability to place most Uk accents and dialects within less than 5 miles of location. Comes I think from being an army brat and moving all over Uk and having to be able to understand lots of different accents, dialect and slang
If deaf people all over the world speak the same sign language
No they don't not even across other English speaking countries (or indeed Spanish, french etc countries) also sign language has a different grammar etc to the language of the nation where it's spoken. I have BSL qualifications but I'm nowhere near as proficient as my deaf signing friends.