Is it unethical to submit for review multiple articles which overlap in some respect? I am well aware of the ethic guidelines in the academic publishing world regarding submission for publication of the same article to multiple journals: I know this is broadly considered unethical and creates a bad reputation for the author in question among the academic community (this eventually giving way to negative repercussions –presumably and informal, tacit type of ‘black listing’).

I have a slightly different problem here: 

I am wondering what happens if I submit a series of articles, one different article to one different publisher, but all of them more or less at the same time: each of these articles would consist of a theoretical premise (a formula of principles according to which a text’s analysis will be conducted in the article), which is common to all the articles in object, and then the main body, different in every article: that would be the analysis itself (on the basis of the formula) of the works of an author –a different author in every article.

The field of research is humanities (literature). I am attempting to determine, on the basis of existing definitions of a literary trend (the aforementioned formula, which itself is a sum up of existing definitions of the literary trend, by other researchers), which authors and which works of theirs may be plausibly associable to the trend.

So, to sum it up, the formula of analysis (the definition of the trend) is the introductory part of each article. Conceptually speaking it is the same for all of them. I could change the exposition from one article to the other for the sake of not using the same exact text in all articles. The concept(the theoretic formula), however would remain the same: it would mostly not be my own original contribution, give or take a few corrections or specifications I am adding. The main body of the text –the original contribution to knowledge- is the analysis of the author’s text: this is the greatest part of the text and it is different for each article (one author for every article).

Much of this research has already been done in a draft form. Hopefully at some point in the future, and if these texts are published as articles, I’d be able to organize them (along with a few necessary additions) into a broader text to be submitted for publishing as a book.

So the question is: would this strategy be viewed by any reviewer/publisher/editor as a breach of ethic guidelines in the academic publishing sector? Would it cause me problems of reputation in it?
You should avoid self-plagiarism. Having an identical section in both papers would be ethically questionable. They could have the same overall meaning, but I would try to rephrase them differently as you might already have done.
Also have your papers cite each other as being submitted, and possibly update the final manuscript with full citations.
It may be a good idea to let the journal editor know that this is happening. They may be able to provide you with specific guidelines.