running power to outside workshop
I have a large barn with a 100 amp electrical service. I also have a work shop (shed) about 150 feet away. I would like to run power from the barn to the work shop to run power tools (bench grinder, small drill press, sawzall, small portable air compressor, etc). I would like to run the wire overhead (about 15 feet in the air, attached to steel aviation cable which is attached snugly from barn to workshop) VS underground. My thoughts are to run 10/2 romex out of a 30 amp breaker from the barn box into a small sub-panel installed in the workshop. However, I want a 30 amp breaker in the subpanel and I'm not sure if I should have two breakers on one line. Also, I'm not sure if romex can be used outside above ground. Any suggestions, as far as the type of wire I should use, the size wire, or any pros or cons with my plans would be greatly appreciated. I am obviously not an electrician, but I have some knowledge of electrical hook ups. Thank you in advance for any help.