R - do I need to add explicit new line character with print()?

When you simply print out a vector, the nature of R is such that you're never going to have a newline in a character vector.

> print("hello
world
")
 [1] "hello
world
"
That is, the newlines are in the string, they just don't get printed as new lines. However, you can use other functions if you want to print them, such as cat:
> cat("hello
world
") hello world
You can also use the writelines() function as follows: 

writeLines("hello
world")hello
world