They are just trying to use NU name to increase their traffic. Just like the case with the fake wuxiaworld website. From the pictures on the store it seems they are an aggregator app, stealing the works of translators. If you want really a NU app.. there have a thread about "how to make your own free nu app" in the tuto and resource forum
There is. Though that app is not in synched with the browser novel updates (e.g. your library, etc.) .. and apparently it's not the official one, as stated above. XD