Is a spinner allowed to bowl a bouncer above the shoulder of the batsman?
Bowling rules do not change by bowling type. So a bowler is allowed to bowl two bouncers in an over(in Test and ODI) and one in T20I in an over irrespective of bowling type. That means if a bowler bowls more than allowed bouncers in an over, it will be called a no ball.
Spinner can also bowl any type of bowls which other bowlers bowls. There is no restriction. Spinners sometime bowl yorker or bouncer depending on the situation of the match. I remember many spinners using at least yorkers in matches.