Translation:Friendliness will always be an advantage.
I learned that "luôn" is often and "luôn luôn" is always. Is that wrong?
Thường or thường thường are often. Luôn and luôn luôn are always.
Nope, you're right, but I think luôn luôn is more of an emphasis on luôn
That is correct.
Friendliness will always be an advantage
No need to add "sự". Short and to the point should be:
Thân thiện luôn là một lợi thế.