Question: How groff can output `\` symbol in my text, do not reading this symbol as a macro?
And how to prohibit dividing words with a dash (hyphenation)?

Answer: 
You can get a printing version of the backslash with `\e` according to the manpage.

And there is `.nh` for »no hyphenation«.
For me, writing `\\` as a sort of *escape sequence* works fine and outputs a singe backslash "\".