Probably grams-cm, which you can convert to newton-meters. Very hard to tell unless you quote the actual motor.
To provide you with high torque at stand-still. Gimbals almost don’t move, they just kind of twitch about a rad. If you have very low resistance, you will immediately burn the coils. And no, the gimbals cannot be compared with low ohm high speed motors. The regime is very different. Also gimbals draw very low current, anything over 5A is probably either a gigantic gimbal or not a gimbal motor. While, the low ohm motors easily draw 50A and devlop the power at very high speed.
If I were you I’d use a dynanometer or just a home hand-scale and measure it instead of calculating anything.
Yes, this is very common. The MIT Cheetah actuator is not exactly a gimbal but close.
Here is another example with an 80mm gimbal.
Cheers,
Valentine