Advice needed. NLP and ML. Where to start?
As far as I can see, your reading list lacks specific NLP introductions. A really good starting point is Dan Jurafsky and Chris Manning's Coursera course (for example here https://www.youtube.com/watch?v=nfoudtpBV68 ). This specifically covers spell checking in one of the first videos. 

In general, spell checking is a rather easy task, while (convincing) text generation is a lot harder. Grammar checking should be easy in theory but I'm not sure about that. Concerning proofreading, I'm not completely sure what you mean by that. Does this extend over spell and grammar checking, in your point of view?

Artistic style transfer is possible although I'm not sure what the current state of the art. You could be more luckily diving into stylometry (https://en.wikipedia.org/wiki/Stylometry) there.

A really good NLP text book to start with is Jurafsky and Martin: Speech and Language Processing (specifically covering generation). 1st edition is publicly available as pdf (just google). But there is also a 2nd edition and they are currently working on a 3rd (the chapters they are done writing are freely available as well).