Under FAR/JAR 25 certification rules, take-off performance is limited by the most restrictive case of engine-out performance (climb, obstacle, brake energy, structure, field length OR 115% of the all engines operating take-off run to 35 feet above the runway elevation. Four engine planes can be limited by all engines case more frequently than twins. Reason being the four-engine planes lose only 25% of their thrust while twins lose 50% and probably something on the order of 80% of their excess thrust making the OEI case more restrictive for twins.
Need more detail to answer the second question.
GF
Did I do OK, J_T?