Can someone please help me with the following questions that deal with regional economics?

1. Some economists have hypothesized that cities will reach some optimal size as firms and people move to or away from them. Why might a city never reach this theoretical optimal size? Do cities tend to grow larger or stay smaller than their theoretical optimal size?

2. If the output from a land source brings revenue of $1100, transport costs of shipping this output to the market are $100, non-land payments are $200 and the land used in production is 4 acres, what will the possible rent for this land be according to the von Thunen model?

3. Suppose that we can identify the following four groups of people in a society: Students, retirees, families with two working parents with no children and families with one working parent with children. In your opinion, what will be the relative slopes of the bid-rent curves for these groups? Explain your opinion fully.