They illustrate the concept that regulation of translation can occur by several different mechanisms. The answers are present in the chapter. Not 'capping' the RNA can inhibit mRNA translation. Excess free heme increases the rate of translation of hemoglobin messages. Some receptors span the bilayer and on their intracellular side they have a domain that can function as a protein kinase.
Some receptors can move from the cytoplasm to the nucleus.
Some receptors bind to effector proteins that generate a second messenger molecule. MEK would never get phosphorylated. MAPk kinase would typically be present in the nucleus. Binding of growth factor to the growth factor receptor would fail to activate the receptor. All of the above.