Is it hard to get a job in the US with a foreign engineering degree?

It depends on the branch or specialty. Most employers would like to see if you also have a graduate degree from a US university. Also if you can pass and obtain a professional engineering license. If you have a degree from an internationally known university such as Ecole Polytechnique.

Yes, they need the person has local US working experience in engineering firm, besides, you need to apply a US engineering license before allow to work in a proper firm.

The easiest path towards tech employment in the US is software development. The demand for civil and environmental engineers is in reasonable balance with the supply, and the supply of mechanical engineers only slightly exceeds the supply; in other branches, such as electrical, chemical, petroleum, and biomedical engineering, the competition for jobs is much tougher. In computer programming, the demand for workers definitely exceeds the supply, so if you have good programming skills, it hardly matters what degree you have.

Does the degree holder have a green card or is a US citizen? Does the degree holder speak English well? Answer depends on those two.

It depends where you live in all honesty but engineering degrees are fairly common. A high gpa won't help you as much as experiences and references will. Be sure to get numbers of colleagues who will vouche for you.