$1.$What is the $"4\%"$ Rule?

$2.$How can you use the $"4\%$ Rule" to determine the size of the financial nest$-$egg you will need to accumulate prior to retirement?

$3.$How would a decrease in such a rule$-$of$-$thumb, from $4\%$ to $3\%$ for example, have on the size of the nest$-$egg that a retiree must accumulate prior to retirement?$4.$There is currently much discussion in the personal finance arena on the topic of F$.$I.R$.$E$.($Financial Independence Retire Early$).$ Would retiring early have any impact on the withdrawal rate a person should assume?

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