If both the president and the vice president are unable to serve who becomes president

no , per capita income is not a true measure of the development because: -it only tells us about average income not how income is distributed among the people.it only give us an idea of the economic aspect.it is only at the qualitative basis.moreover, income is not only the way of development other factors are also as much as important as income.

this is a pretty broad question and can be a pretty lengthy answer. since 1900, women have gained a lot more rights and have become active in the workforce. with women being in the workforce, men play a larger role in family life. many family tasks are shared between men and women, whereas, women used to be the sole family caretakers.

that should get you started at least.