Devine formula — Men: 50 + 2.3 × (inches over 5ft); Women: 45.5 + 2.3 × (inches over 5ft)
Man, 5'10" (10 inches over 5ft): 50 + 2.3×10 = 73 kg.
No, other formulas (Robinson, Miller, Hamwi) exist and give slightly different results; Devine is the most widely used clinically.
No, it's based purely on height; muscular individuals may exceed this figure while remaining healthy.