Yes.
"Gram" can be a noun, typically referring to a unit of weight in the metric system equal to one thousandth of a kilogram. It can also be a colloquial term for a grandmother.
Kg (kilogram) is the standard - although it is not a standard of weight, but of mass. The kilogram is used world-wide as the standard of mass. It is part of the SI (the International System of units).
A gram is part of the metric system. It is the unit of measure for weight.
No, feet are not part of the metric system.
Inches are part of the English system and centimeters are part of the metric system.
The milligram is part of the SI system of measurements, it represents 1/1000 of a gram. One gram is the weight of one milliliter of pure water at 4 C. So the answer is no. The metric system is international, not US.
Imperial and metric
Centimetres are part of the metric system. A centimetre is 0.01 metre.
A pound is part of the imperial system of measurements, which were used in England, and elsewhere, before the introduction of metric measurements.
No, a kilogram is a standard unit of mass, not volume. Volume is typically measured in units such as liters or cubic meters.
It already is part of the metric system