Well, the first question is easy: from the invaluable
Letters of JRR Tolkien,
ed H Carpenter & C Tolkien ;
256: From a letter to Colin Bailey, 13 May 1964
(An account of Tolkien's unfinished story
'The New Shadow').
I did begin a story placed about 100 years after the Downfall [of Mordor], but it proved both sinister and depressing. Since we are dealing with Men it is inevitable that we should be concerned with the most regrettable feature of their nature: their quick satiety with good. So that the people of Gondor in times of peace, justice and prosperity, would become discontented and restless – while the dynasts descended from Aragorn would become just kings and governors – like Denethor or worse. I found that even so early there was an outcrop of revolutionary plots, about a centre of secret Satanistic religion; while Gondorian boys were playing at being Orcs and going round doing damage. I could have written a 'thriller' about the plot and its discovery and overthrow – but it would be just that. Not worth doing.
Second question? No. Just no.
Even if the Tolkien Estate would agree to it, (unlikely after seeing what happened to the film rights, which the Estate have no control over after being sold for a pittance by JRRT himself) it wouldn't be a Tolkien story, and, I think, would be seen by the majority of Tolkien devotees as a crass attempt to cash in on the name.