Based on the spot price of $16 and the strike price $18 as well as the fact that the risk-free interest rate is 6% per annum with continuous compounding, please undertake option valuations and answer related questions according to following instructions: Assume that over each of the next two four-month periods, the share price is expected to go up by 11% or down by 10%.

1. Use a two-step binomial tree to calculate the value of an eight-month European call option using risk-neutral valuation.
2. Use a two-step binomial tree to calculate the value of an eight-month European put option using risk-neutral valuation.
3. Use a two-step binomial tree to calculate the value of an eight-month American put option.
4. Calculate the deltas of the European put and the European call at the different nodes of the binomial tree.