Given a long-run average total cost function where (let's say) function is U-shaped and minimized at q=4 units of output, long-run average total cost is $100 at q=4. and the market demand for unit is Qd = 1000 - 2P (perfectly competitive industry)

How would I find:

long-run equilibrium output of each firm

long-run equilibrium price

long-run equilibrium total industry output

long-run equilibrium number of firms in the market

long-run equilibrium profit of each individual firm

long-run equilibrium value of consumers' surplus

*why is the function 'U' shaped?*