A penny can be used to measure for safe tread depth on your car tires. Hold the penny upside-down in a tread groove. If the top of Lincoln's head is visible above the tread wall, the tires are completely worn out, and need to be replaced, pronto.
milligrams
Millimeters.
Coins are measured in millimetres.
Millimetres, as in 1.5 mm. You could use a micrometer to measure thickness of a coin.
Usually you would weigh it, on a device that is calibrated to show mass.
Personally, what I would do would be to experimentally find a lead fishing sinker, rock, gold coin etc., which, when added to the irregular object, sinks them both. For accuracy, the object selected should be smaller than the irregular object. The smaller, the better. Then, in the usual way, find the volume of the sinker, the rock, or the gold coin alone. Write it down so I don't forget it. Finally, glue the 'ballast' to the irregular object, and measure the volume of the combination by sinking it. From the volume I find, subtract the volume of the ballast alone, and I'll have the volume of the irregular object.
Making a coin levitate with no physical interaction would be done through telekinesis. Telekinesis is the process of moving an object with your mind and is often though to be a fabled process.
Micrometer.
Yes
The mass of any coin is typically measured in grams; the capacity or volume would be measured in millilitres.
With a micrometer (caliper) To measure the thinkness you use mm's
No. You, the coin, and the bus are all travelling at the same velocity. You toss the coin and it goes up and down. That is what you see from your position. If you were standing outside the bus, the coin would appear to travel in a parabola. Inertia only describes how an object is accelerated. Newton's Second law states that force = mass * acceleration. This means that it requires a force to accelerate an object. That is the perception of inertia.