Yes it is glossy, in fact a good rule of thumb is that ALL metallics and transparent colors will dry glossy. This Chrome color will be VERY bright, especially in direct sunlight!
A clear coat will not be necessary unless you have applied/will apply some delicate weathering to the surface (such as chalks). But usually decals would be applied before weathering anyways.
Be sure to mask off and paint some contrasting panels on the plane lighter and darker shades, or it could end up looking very toylike due to the bright finish.
American aircraft used a much higher quality aluminum in their skins than other countries. Look at any bare-metal US AC from WW2 or the Korean war for example, German AC metal tended to look very greyish in its finish.
Due to weathering, your surface should look anywhere from bright and clean to dull and scratchy, depending on the amount of service the model would intend to depict. But even straight from the factory, a bare-metal plane would show a tiny amount of scuffing around wing-walks, cowl panels and other high traffic areas. Period photos of in-service AC will give you some inspiration in your painting/weathering endeavors.
Good luck!