They have a limited number of fighter ships, but i can bet carrier class cruisers would come into production prety quick. Their ships are fitted for war against the covenant, and other advanced weaponry. The UNSC could easily kick the butts of the Empire. Also they have the ability to make pinpoint jumps across systems that are arguably better then the empires ability.
They basically copy what they see and use it to the best of their knoledge. But their Troops are not as cunning or smart as the humans of the empire or UNSC. According to the books for the Halo universe any of the larger battleships of the Covenant can destroy all life on the surface of a planet with their plasma weapons.
They were kicking the butts of the UNSC in the novels (4th book might change that, but we have to see).
