The model represents the as-launched Enterprise, with the bee-hive island.
The kit was originally released in the mid-60s by Aurora. Monogram got the Aurora molds when Aurora folded and the kit was re-released uner the Monogram label. Later when Monogram and Revell merged, Revell got access to the molds. The kit has been released under the Revell/USA as well as the Revell/Germany labels. It is the same kit -- with few, if any, updates. It is prime 1960s state of the art.
Bert Kinsey in his Detail & Scale book on the USS Enterprise called the Aurora/Monogram/Revell Enterprise the second-best model in that scale. There were only two. The other was the Otaki (now Arii) kit. It was head & shoulders better.
There are no dedicated aftermarket sets for the 1:400 scale Enterprise. There are several 1:400 PE sets which can cobbled together to begin to fill the bill. No modern aricraft are available.