If the number of producers increases then we can expect the supply curve to shift outward to the right, thus increasing the supply at every price.
But this additional supply may result in a surplus and the extra completion may cause prices to drop.
If the price of Hot Dogs goes up then we can expect the demand curve for hot dog buns a complimentary good to shift inward and to the left. The resulting reduction in demand will result in a surplus and so we may see both a fall I in the demand and the price for both Hot Dogs and the complimentary good Hot Dog Buns.
Do I have these two scenarios correct? I am trying to fully understand Shifts in Supply Curves and Shifts in Demand Curves vs Quantity Supplied or Quantity Demanded