66Kg

You really cannot tell how much the suitcase can hold in mass. 66 litres is the volume of the suitcase. The answer would be 66 kg if you were carrying water, but I think the actual weight limit is going to be far less, otherwise the suitcase would be capable of carrying the weight of a typical teenager (145 lb)

No, it is a noun. But it can be an adjunct (suitcase handle, suitcase rack).

pulling a wheeled suitcase. carrying a suitcase is not scientifically categorized as work.

a papier mache suitcase is a suitcase made using the paper mache technique.

A suitcase with wheels.