"Benevolent" is from very old English, and I rarely hear it said in everyday conversation. The short answer is no, it is not a natural thing to say in modern times.

No. That phrase seems charmingly quaint or old-fashioned. It's something you might read in a Victorian novel, like those of Charles Dickens, and seems more appropriate for old people and authority figures, not for a friend. "There in the department store was a man dressed up as Santa Claus with a benevolent gleam in his eye." "My grandfather James is a courtly, benevolent old gentleman, but my grandfather John is a crabby old curmudgeon." In plain (and slightly colloquial) language: "My friend is a kind person." "My friend is a nice guy." If your friend does a lot of charity work or volunteer work in the community, "My friend is a real giver," or "My friend likes to give back," or "My friend likes to help others." If your friend is the kind of person who thinks there is good in everyone, "My friend thinks the best of everyone." If your friend is wealthy enough to give important amounts of money for community projects, "My friend is a philanthropist." Oddly enough, when I hear the word "benevolent" the first thing that pops into my mind is "benevolent despot."