Buybacks in general are bad for everyone involved because they're often done when valuations are high, however, they can be beneficial to shareholders when valuations are low.
Shorting helps facilitate price discovery and options are used to protect against large downside risks.
> Hedge funds, as a class, underperform the market, partly because of their excessive fees.
You're thinking of mutual funds. Hedge funds as a class do outperform the market, even after fees.